Category: Medicine

On scientific beliefs, Indigenous knowledge, and paternity.

On scientific beliefs, Indigenous knowledge, and paternity.

Recently my spouse & I reviewed Jennifer Raff’s Origin: A Genetic History of the Americas for the American Biology Teacher magazine (in brief: Raff’s book is lovely, you should read it! I’ll include a link to our review once it’s published!), which deftly balances twin goals of disseminating scientific findings and honoring traditional knowledge.

By the time European immigrants reached the Americas, many of the people living here told stories suggesting that their ancestors had always inhabited these lands. This is not literally true. We have very good evidence that all human species – including Homo sapiens, Homo neaderthalensis, and Homo denisovans among possible others – first lived in Africa. Their descendants then migrated around the globe over a period of a few hundred thousand years.

As best we know, no lasting population of humans reached the Americas until about twenty thousand years ago (by which time most human species had gone extinct – only Homo sapiens remained).

During the most recent ice age, a few thousand humans lived in an isolated, Texas-sized grassland called Beringia for perhaps a few thousand years. They were cut off from other humans to the west and an entire continent to the east by glacial ice sheets. By about twenty thousand years ago, though, some members of this group ventured south by boat and established new homes along the shoreline.

By about ten thousand years ago, and perhaps earlier, descendants of these travelers reached the southern tip of South America, the eastern seaboard of North America, and everywhere between. This spread was likely quite rapid (from the perspective of an evolutionary biologist) based on the diversity of local languages that had developed by the time Europeans arrived, about five hundred years ago.

So, by the time Europeans arrived, some groups of people had probably been living in place for nearly 10,000 years. This is not “always” from a scientific perspective, which judges our planet to be over 4,000,000,000 years old. But this is “always” when in conversation with an immigrant who believes the planet to be about 4,000 years old. Compared with Isaac Newton’s interpretation of Genesis, the First People had been living here long before God created Adam and Eve.

If “In the beginning …” marks the beginning of time, then, yes, their people had always lived here.

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I found myself reflecting on the balance between scientific & traditional knowledge while reading Gabriel Andrade’s essay, “How ‘Indigenous Ways of Knowing’ Works in Venezuela.” Andrade describes his interactions with students who hold the traditional belief in partible paternity: that semen is the stuff of life from which human babies are formed, and so every cis-man who ejaculates during penetrative sex with a pregnant person becomes a father to the child.

Such beliefs might have been common among ancient humans – from their behavior, it appears that contemporary chimpanzees might also hold similar beliefs – and were almost certainly widespread among the First Peoples of South America.

I appreciate partible paternity because, although this belief is often framed in misogynistic language – inaccurately grandiose claims about the role of semen in fetal development, often while ignoring the huge contribution of a pregnant person’s body – the belief makes the world better. People who are or might become pregnant are given more freedom. Other parents, typically men, are encouraged to help many children.

Replacing belief in partible paternity with a scientifically “correct” understanding of reproduction would probably make the world worse – people who might become pregnant would be permitted less freedom, and potential parents might cease to aid children whom they didn’t know to be their own genetic offspring.

Also, the traditional knowledge – belief in partible paternity – might be correct.

Obviously, there’s a question of relationships – what makes someone a parent? But I also mean something more biological — a human child actually can have three or more genetic contributors among their parents.

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Presumably you know the scientific version of human reproduction. To wit: a single sperm cell merges with a single egg cell. This egg rapidly changes to exclude all the other sperm cells surrounding it, then implants in the uterine lining. Over the next nine months, this pluripotent cell divides repeatedly to form the entire body of a child. The resulting child has exactly two parents. Every cell in the child’s body has the same 3 billion base pair long genome.

No scientist believes in this simplified version. For instance, every time a cell divides, the entire genome must be copied – each time, this process will create a few mistakes. By the time a human child is ready to be born, their cells will have divided so many times that the genome of a cell in the hand is different from the genome of a cell in the liver or in the brain.

In Unique, David Linden writes that:

Until recently, reading someone’s DNA required a goodly amount of it: you’d take a blood draw or a cheek swab and pool the DNA from many cells before loading it into the sequencing machine.

However, in recent years it has become possible to read the complete sequence of DNA, all three billion or so nucleotides, from individual cells, such as a single skin cell or neuron. With this technique in hand, Christopher Walsh and his coworkers at Boston Children’s Hopsital and Harvard Medical School isolated thirty-six individual neurons from three healthy postmortem human brains and then determined the complete genetic sequence for each of them.

This revealed that no two neurons had exactly the same DNA sequence. In fact, each neuron harbored, on average, about 1,500 single-nucleotide mutations. That’s 1,500 nucleotides out of a total of three billion in the entire genome – a very low rate, but those mutations can have important consequences. For example, one was in a gene that instructs the production of an ion channel protein that’s crucial for electrical signaling in neurons. If this mutation were present in a group of neurons, instead of just one, it could cause epilepsy.

No human has a genome: we are composite creatures.

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Most scientists do believe that all these unique individual genomes inside your cells were composed by combining genetic information from your two parents and then layering on novel mutations. But we don’t know how often this is false.

Pluripotent (“able to form many things”) cells from a developing human embryo / fetus / baby can travel throughout a pregnant person’s body. This is quite common – most people with XX chromosomes who have given birth to people with XY chromosomes will have cells with Y chromosomes in their brains. During the gestation of twins, the twins often swap cells (and therefore genomes).

At the time of birth, most humans aren’t twins, but many of us do start that way. There’s only a one in fifty chance of twin birth following a dizygotic pregnancy (the fertilization of two or more eggs cells released during a single ovulation). Usually what happens next is a merger or absorption of one set of these cells by another, resulting in a single child. When this occurs, different regions of a person’s body end up with distinct genetic lineages, but it’s difficult to identify. Before the advent of genetic sequencing, you might notice only if there was a difference in eye, skin, or hair color from one part of a person’s body to the next. Even now, you’ll only notice if you sequence full genomes from several regions of a person’s body and find that they’re distinct.

For a person to have more than two genetic contributors, there would have to be a dizygotic pregnancy in which sperm cells from unique individuals merged with the two eggs.

In the United States, where the dominant culture is such that people who are trying to get pregnant are exhorted not to mate with multiple individuals, studies conducted in the 1990s found that at least one set of every few hundred twins had separate fathers (termed “heteropaternal superfecundication”). In these cases, the children almost certainly had genomes derived from the genetic contributions of three separate people (although each individual cell in the children’s bodies would have a genome derived from only two genetic contributors).

So, we actually know that partible paternity is real. Because it’s so difficult to notice, our current estimates are probably lower bounds. If 1:400 were the rate among live twins, probably that many dizygotic pregnancies in the United States also result from three or more genetic contributors. Probably this frequency is higher in cultures that celebrate rather than castigate this practice.

Honestly, I could be persuaded that estimates ranging anywhere from 1:20 to 1:4,000 were reasonable for the frequency that individuals from these cultures have three or more genetic contributors.** We just don’t know.

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I agree with Gabriel Andrade that we’d like for medical students who grew up believing in partible paternity to benefit from our scientific understanding of genetics and inheritance – this scientific knowledge will help them help their patients. But I also believe that, even in this extreme case, the traditional knowledge should be respected. It’s not as inaccurate as we might reflexively believe!

The scientific uncertainty I’ve described above doesn’t quite match the traditional knowledge, though. A person can only receive genetic inheritance from, ahem, mating events that happen during ovulation, whereas partible paternity belief systems also treat everyone who has sex with the pregnant person over the next few months as a parent, too.

But there’s a big difference between contributing genes and being a parent. In Our Transgenic Future: Spider Goats, Genetic Modification, and the Will to Change Nature, Lisa Jean Moore discusses the many parents who have helped raise the three children she conceived through artificial insemination. Even after Moore’s romantic relationships with some of these people ended, they remained parents to her children. The parental bond, like all human relationships, is created by the relationship itself.

This should go without saying, but: foster families are families. Adopted families are families. Families are families.

Partible paternity is a belief that makes itself real.

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** A note on the math: Dizygotic fertilization appears to account for 1:10 human births, and in each of these cases there is probably at least some degree of chimerism in the resulting child. My upper estimate for the frequency that individuals have three or more genetic contributors, 1:20, would be if sperm from multiple individuals had exactly equal probabilities of fertilizing each of the two egg cells. My lower estimate of 1:4,000 would be if dizygotic fertilization from multiple individuals had the same odds as the 1:400 that fraternal twin pairs in the U.S. have distinct primary genetic contributors. Presumably a culture that actively pursues partible paternity would have a higher rate than this, but we don’t know for sure. And in any case, these are large numbers! Up to 5% of people from these cultures might actually have three or more genetic contributors, which is both biologically relevant and something that we’d be likely to overlook if we ignored the traditional Indigenous knowledge about partible paternity.

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header image from Zappy’s Technology Solution on flickr

On Long Covid, minds, and bodies.

On Long Covid, minds, and bodies.

After “recovering” from Covid-19, many people have suffered lingering malaise: labored breathing, foggy thoughts, chronic fatigue.

It’s awful, and it’s ill-understood. Trials are ongoing to try to help people, but, honestly, medical doctors don’t know what to do. Akiko Iwasaki, an immunologist at Yale, has been investigating Long Covid since late 2020 and has a long list of experimental therapies that her team would like to test.

In an interview with Jennifer Couzin-Frankel for Science magazine, Iwasaki said “As a basic scientist, of course I’d like to have all the pieces of the puzzle” before giving people untested therapies, “but the patients, they cannot wait.”

Unfortunately, longstanding prejudice in the medical community about what counts as a “real” disease has meant that a promising medication, Prazosin, apparently isn’t even on the list of therapies to try.

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Full recovery from an upper respiratory infection like influenza or Covid-19 often takes months. This timeline is very noticeable among athletes, whose performance is exquisitely sensitive to any disturbances in breathing. Even though young people recover from many illnesses much more quickly than others, an elite high school athlete who catches a bad respiratory infection will often suffer for an entire sports season.

This is after the acute phase of coughing and viral production has passed: bodies can take a long time to heal.

Diabetes, heart damage, and a wide range of autoimmune conditions can also be triggered by viral infections (or, often, a body’s immune response to viral infection). Even after a virus has been cleared from a person’s body, the collateral damage caused by the infection or the person’s immune response can result in lingering maladies.

We shouldn’t be surprised that a wide range of persistent problems would appear after the vast majority of the world’s population just had their first encounter (and second, and third …) with a novel coronavirus.

Also, common symptoms of Long Covid – sleep disturbances, muddled thoughts, chronic fatigue, unexpectedly low cortisol, “odd” immune responses, gastrointestinal distress – match common symptoms of PTSD. For many people, Long Covid probably is PTSD.

Please note that I’m not saying that Long Covid isn’t real!

PTSD is real. PTSD causes real physical effects. But for some reason – perhaps because PTSD has a partly psychological origin – PTSD is often considered a less meaningful condition by both the professional medical community and our society at large.

In an opinion essay for the New York Times – “If You’re Suffering After Being Sick with Covid, It’s Not Just in Your Head” – sociologist Zeynep Tufekci inadvertently perpetuates this prejudice, the idea that conditions that have mental causes aren’t as important. I don’t believe that this was Tufekci’s intent – after all, she does an excellent job listing many conditions that the medical community incorrectly discounted in the past.

But conditions that target the brain matter, too! Honestly, it shouldn’t be a hard sell to convince people that brains are at least as important to the human experience as kidneys, lungs, livers, or arteries.

And yet, here we are, living in a world where migraines, depression, or PTSD are considered less “real” than other conditions.

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Most likely, what we’ve been calling Long Covid will turn out to be a variety of different conditions. Some people have suffered inflammation or damage to their hearts or lungs that will last a long while after viral clearance. Some people are experiencing the opportunistic reactivation of other latent viruses.

But many cases of Long Covid are probably PTSD. Which is a real condition, with real physiological effects, and there are real medications – like the blood pressure medication Prazosin – that can help in recovery.

We shouldn’t let prejudice about which conditions count keep people from the treatments they need.

On urgency and gender-affirming medical care.

On urgency and gender-affirming medical care.

In the New York Times Magazine article “The Battle Over Gender Therapy,” journalist Emily Bazelon describes the conflicting views of several medical doctors and psychologists. They disagree over timing and access: who should decide whether a young person receives gender-affirming medical care, and how long should this decision-making process take?

In general, waiting before finalizing a decision is best. This is true whether they are big decisions – like getting married or buying a house – or relatively small decisions – like buying a new couch, posting an irate Twitter message, or drinking another beer. If you can give yourself time to mull it over, you’ll probably be happier with your resulting decision, even if you end up doing the same thing.

In the film Searching for Bobby Fischer, a chess instructor attempts to teach this patience to his student:

“So what’s your best move?”

“Rook to d.”

“What about taking on e?”

“What about it?”

“You didn’t consider it. You’re still not considering it.”

“I’m right. Rook to d is the best move.”

“You didn’t study the board!”

Even when the answer seems clear, it’s still often better to take time to think. To plan, to weigh options.

But we don’t always have this luxury. Sometimes, when considering whether to buy a house, people feel forced to make a decision immediately – otherwise, someone else might buy it! These snap decisions, like the home purchases that many people made during the pandemic, are more likely to lead to regret.

For a person seeking gender-affirming medical care, deciding to begin hormone therapy might be an even bigger decision than getting married or buying a house. Hormone therapy can cause irreversible physical changes. For a person who was assigned female at birth, taking testosterone often results in a permanently deeper voice; reshaping of the face to appear more angular; changes in the shape and size of genitals.

Similarly, when a person who was assigned male at birth uses hormone therapy to help their appearance and physiology better match the gender of their brain, an analogous set of changes may linger even if this person decides to stop taking the medications.

And, yes, some people will decide to stop taking the medications. As with any medical treatment, hormone therapy has both benefits and side-effects, and it’s hard to know how these will balance out for a particular individual’s brain & body before they try.

So, it’s a big decision. There are irreversible changes. Obviously, taking a lot of time to wait and evaluate would be best, right?

But sometimes, competing urgency makes waiting impractical. As an example, consider surgical removal of an organ. This is a drastic measure: you’d like to wait and mull things over. Unfortunately, time pressure from the septic shock of an advanced bacterial infection might force a quick decision. My friend was barely conscious during this decision-making process after collapsing in the lobby of our local hospital.

When deciding whether or not to initiate gender-affirming hormone therapy, there’s a bit more wiggle room. But for a young person who’s mustered up enough self-knowledge and courage to talk to their parents or healthcare provider about wanting medication, there is still looming time pressure.

During puberty, bodies can change very drastically within a matter of months. Many of these changes are lifelong and irreversible. Waiting to evaluate isn’t just a default, low-impact choice. Hormone therapy is a big deal, but waiting will also bring dramatic, permanent physiological changes. Not to mention continued psychological turmoil, which might be compounded by the knowledge that, for all of your bravery in speaking up, you’re still not getting the help you need.

My main qualm with Bazelon’s article? For all the nuance devoted to the medical doctors’ and psychologists’ opinions, we hear very little from young people. Bazelon interviewed over 60 clinicians, researchers, activists, and historians, but only half that many of the young people whose brains, bodies, & lives are at stake. As a parent, I’m aware that children can do or say a lot of irksome, irrational things; as someone who works with elementary and high-school students, I also know that we have to recognize young people as valid knowers and thinkers.

I want to hear about the sense of urgency from young people themselves. Instead, this central issue was only passingly mentioned in a single sentence, a quote from child psychologist Laura Edwards-Leeper about the process of evaluating young people for gender-affirming treatment: “If a child was on the cusp of puberty, and anxious about how their body was about to change, we tried to squeeze them in faster, which I still think is really important.”

Young people have a stake in our world. And yet – with our inaction on climate change; our mass production & sale of military-grade weaponry to anybody who wants it; our treating schools as a lower priority than bars or restaurants during the pandemic, and then keeping schools closed or disrupted even after we had data showing that these disruptions were causing children even greater harm than Covid-19 infection; our age- and wealth-based prejudices that give retirees a far greater say in the future of our country & planet than the young people who will inherit the mess – we are not only disenfranchising young people, but abjectly failing them.

Young people have not been silent. We ought to listen.

On the apparent rise in transgender and non-binary identities.

On the apparent rise in transgender and non-binary identities.

Many more people in the United States now identify as transgender and/or non-binary than in the recent past. This increase is most dramatic among younger generations.

There are two major causes of this change, and for political reasons it’s essential that we acknowledge both.

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My spouse was recently speaking to a colleague and (cheerfully) described the increase as being due to our nation’s changing culture. In my opinion, we still have a long way to go, but many people are much more accepting than in the recent past. As the perceived risk decreases, people will be more likely to reveal their true identities.

But that isn’t the whole story.

The chemical make-up of our world is radically different than in the recent past. As a (lapsed) organic chemist, I’m quite proud of human ingenuity and our ability to synthesize so many wondrous medicines, small molecules, and industrial materials. The technologies we have access to are amazing! We can live so much longer, and our quality of life during that time is pretty awesome.

We’ve dramatically altered the environment, though. Industrial run-off and medicinal metabolites are present at high concentrations in our water supply, including lots of “endocrine disrupting chemicals.”

Endocrine disrupting chemicals often resemble naturally-occurring hormones and signaling molecules. Many of these chemicals are known to induce non-binary sexual development among other animals – in recent years, there’s been a dramatic increase in the proportion of wild animals born with intersex characteristics.

We humans are also susceptible to this altered chemical milieu. The environment in which human brains and bodies develop during gestation is chemically different now from in our recent past.

As epidemiologist Shanna Swan writes in Countdown: How Our Modern World Is Threatening Sperm Counts, “The changes in sexual development taking place all over the world appear to have been accompanied by an apparent rise in gender fluidity …”

Intersex is different from transgender or nonbinary. “Intersex” describes physical morphology and can be assessed for non-human animals; “transgender” and “nonbinary” describe what’s going on inside a person’s brain. But brains are a product of biological development. It’s reasonable to assume – although it would obviously be unethical to test or prove – that endocrine disrupting chemicals capable of changing external sexual morphology also impact developing brains.

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Children are more likely to self-identify as transgender or non-binary now than in the recent past, partly because they are growing up in a different culture, partly because their brains and bodies developed in a different chemical environment.

We don’t yet know how much of the shift has been caused by which factor: maybe the explanation is 10% cultural, 90% biological; maybe both contribute equally; maybe the shift is more due to culture than biology.

But it’s essential for us to acknowledge both contributions – especially because a large portion of our nation’s population espouses conservative or traditional values that decry the cultural change.

Yes, the Democratic party’s policies celebrating diversity have shifted the culture; the Republican party’s policies promoting business and minimizing environmental regulation have shifted the chemical environment.

Whether or not we are happy that gender fluidity is on the rise, it’s important to note that both major political parties in this country have contributed.

I’m no biological determinist – from my perspective as a masculine autistic person who’s chosen to focus on caretaking, I like to imagine that I’m transcending my biological inclinations – but those of us who celebrate liberal values and diversity do ourselves a political disservice if we fail to acknowledge the impact of our shifting environment on gender.

Children will be safer when we make clear that these aspects of their identities aren’t a choice. This is who they are. Personally, I think that’s great. But some people don’t. And so we need to convey that political policies that those people supported helped make children’s lives today different from the way the world used to be.

The way we speak about these issues matters. If we want to include as many people as possible in these conversations – which we must, if we’re going to move forward as a nation – we have to include the whole complex breadth of the world.

Even when it feels uncomfortable.

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Header image by Ted Eytan.

Frog image by John P Clare — although I should acknowledge that not only is this frog living in Ireland, not the U.S., but I’m also not a herpetologist and can’t tell you this frog’s biological sex. But it’s a good looking frog!

On masks and whether they ‘work.’

On masks and whether they ‘work.’

tl;dr – Please get vaccinated, friend!

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My community’s most recent school board meeting was exceptionally contentious.

Public education is almost always contentious in this country: Evolution! The pledge of allegiance! The Founding Fathers’ complicity in felonious (oft murderous) abduction & torture!

Now, we’re also arguing over whether it’s safe for schools to be open at all!

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At the school board meeting, a white woman stood up at the podium, ripped off her mask, and said “I can’t breathe.”

(Unfortunately, I assume the resonance with the BLM protests was intentional. When I went to pick up my kids from school last week, a white mother was wearing a t-shirt with the traditional white on black BLM layout that said “Drunk Wives Matter.” My hometown is within a half hour’s drive of the national KKK headquarters.)

As is the way of things in our country right now, about half the parents in attendance were aghast. The other half cheered.

“The masks don’t work! Everybody knows the masks don’t work!” people shouted.

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Oddly enough, though, the people saying “the masks don’t work” are actually correct. But so are the people who say that masks work. The word “work” is pretty nebulous!

As Joseph Allen & Helen Jenkins wrote in a recent New York Times editorial, many well-meaning people have been unhelpfully vague when defining goals for our pandemic response. Are we trying to minimize lifelong harms from all causes? Are we trying to minimize the number of deaths that occur this year? Are we trying to eradicate the virus that causes Covid-19?

Each of these goals would require that we take a different set of actions.

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Masks “work” in the sense that when people are wearing face masks, there’s a lower probability of Covid-19 transmission during any interaction.

Masks reduce the number of viral particles that exit a person’s airspace as they speak or exhale. Of course, this presupposes that the person wearing a mask actually is shedding viral particles. But that’s the tricky thing about Covid-19 (or influenza)! Some people feel fine!

Masks also might reduce the likelihood of transmission when an unexposed person who is hoping to avoid or delay illness wears a mask. (Masks probably help with this, but it’s less well tested.)

Universal mask requirements are a great tool to delay transmission!

When worn selectively – for instance, only during hospital visits, or only when inside nursing homes – masks can also skew the demographics of transmission. With Covid-19, skewing the demographics of transmission is a great goal!

Even back before we had safe, effective vaccines, we could’ve saved huge numbers of lives by skewing the demographics of transmission! Some people are much more likely to recover from Covid-19 safely than others! (Major risk factors include advanced age, diabetes status, and probably smoking status. But there are also unknown risk factors – we don’t know why certain young healthy people can get so sick from this.)

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Masks don’t “work,” though, if the goal is to prevent cases of Covid-19.

By May of 2020, it was already clear that Covid-19 would become endemic. We’d spread the virus too widely by then. The virus will never go away. Cases will never fall to zero.

Everyone alive today, and everyone born in the future, will be exposed to Covid-19 eventually. (With the possible exception of people who happen to die of other causes within the next few years.)

There’s still a strong argument for using masks to delay Covid-19 transmission: with more time, more people can be vaccinated! The vaccines work, by which I mean that the vaccines save lives.

Everyone will be exposed to Covid-19! The people who have been vaccinated are much more likely to survive! This front page article in my local newspaper is fear mongering; it’s a sort of fear mongering that I wholeheartedly endorse!

Vaccination is a safe, effective, time-tested medical practice. The principles behind vaccination were independently discovered centuries ago by scientists and healers in Africa, India, and China. Their discoveries were the basis for Edward Jenner’s smallpox vaccine.

When scientists say that vaccines “work” – vaccines save lives – we mean something very different than when we say that masks “work” – masks delay exposure!

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In conjunction with vaccination, masks can be helpful!

Which is why the argument that children should currently wear masks in school is reasonable. Covid-19 tends not to be very dangerous for children, but occasionally it’s deadly. There’s a definite cost to wearing masks in school – muffled voices, hidden facial expressions, increased hassle – but children could be kept safer by delaying their exposure to Covid-19 until after a vaccine is approved for them.

(I feel lucky that my kids have already safely recovered from Covid-19 – I’m not beset by the same fear over this that other parents are navigating. But I understand their concern: raising children often feels terrifying because my heart would shatter if anything happened to these tiny, willful, fragile creatures.)

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Most of the people who say “masks don’t work” are planning not to get the Covid-19 vaccine. Which means, weirdly, that they’re right! Without the end goal of eventual vaccination, masks don’t work! Even if universal masking policies were kept in place forever, Covid-19 is so infectious that everyone would still be exposed eventually!

The vaccines can save lives; masks cannot.

Obviously, I’m not arguing that you should ignore local mask requirements: I’m currently wearing a face mask as I type this! And there are lots of people who do want to be vaccinated who don’t have access yet – this isn’t much of an issue for adults in the United States, but vaccine access is an incredible privilege for most of the world’s population.

Because Covid-19 can be transmitted by people who feel fine, wearing a mask is a way to protect others. And personal preference isn’t a good reason to endanger the lives of the folks around us! That’s why we have traffic laws! Even if I think it’d be fun to go out driving while buzzed on booze, or to cruise on the left-hand side of the road, I shouldn’t be allowed to do it!

But also, I think it’s worth acknowledging that, within the full context of their actions, people’s denunciations of masks are actually scientifically accurate.

“Follow the science” is an unhelpful slogan – scientific analysis doesn’t result in a monolithic set of inarguable conclusions. At the heart of any policy, there are goals and priorities. These are set by philosophical or ethical considerations, not scientific fact.

“Follow the scientific findings that help us all achieve my goals for the world” doesn’t have the same pithy ring to it, though.

On vaccination.

On vaccination.

The shape of things determines what they can do. Or, as a molecular biologist would phrase it, “structure determines function.”

In most ways, forks and spoons are similar. They’re made from the same materials, they show up alongside each other in place settings. But a spoon has a curved, solid bowl – you’d use it for soup or ice cream. A fork has prongs and is better suited for stabbing.

In matters of self defense, I’d reach for the fork.

On a much smaller scale, the three-dimensional shapes of a protein determines what it can do.

Each molecule of hemoglobin has a spoon-like pocket that’s just the right size for carrying oxygen, while still allowing the oxygen to wriggle free wherever your cells need it. A developing fetus has hemoglobin that’s shaped differently – when the fetal hemoglobin grabs oxygen, it squeezes more tightly, causing oxygen to pass from a mother to her fetus.

Each “voltage-gated ion channel” in your neurons has a shape that lets it sense incoming electrical signals and pass them forward. Voltage-gated ion channels are like sliding doors. They occasionally open to let in a rush of salt. Because salts are electrically charged, this creates an electric current. The electrical current will cause the next set of doors to open.

Every protein is shaped differently, which lets each do a different job. But they’re all made from the same materials – a long chain of amino acids.

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Your DNA holds the instructions for every protein in your body.

Your DNA is like a big, fancy cookbook – it holds all the recipes, but you might not want to bring it into the kitchen. You wouldn’t want to spill something on it, or get it wet, or otherwise wreck it.

Instead of bringing your nice big cookbook into the kitchen, you might copy a single recipe onto an index card. That way, you can be as messy as you like – if you spill something, you can always write out a new index card later.

And your cells do the same thing. When it’s time to make proteins, your cells copy the recipes. The original cookbook is made from DNA; the index-card-like copies are made from RNA. Then the index cards are shipped out of the nucleus – the library at the center of your cells – into the cytoplasm – the bustling kitchen where proteins are made and do their work.

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When a protein is first made, it’s a long strand of amino acids. Imagine a long rope with assorted junk tied on every few inches. Look, here’s a swath of velcro! Here’s a magnet. Here’s another magnet. Here’s a big plastic knob. Here’s another magnet. Here’s another piece of velcro. And so on.

If you shake this long rope, jostling it the way that a molecule tumbling through our cells gets jostled, the magnets will eventually stick together, and the velcro bits will stick to together, and the big plastic knob will jut out because there’s not enough room for it to fit inside the jumble.

That’s what happens during protein folding. Some amino acids are good at being near water, and those often end up on the outside of the final shape. Some amino acids repel water – like the oil layer of an unshaken oil & vinegar salad dressing – and those often end up on the inside of the final shape.

Other amino acids glue the protein together. The amino acid cysteine will stick to other cysteines. Some amino acids have negatively-charged sidechains, some have positively-charged sidechains, and these attract each other like magnets.

Sounds easy enough!

Except, wait. If you had a long rope with dozens of magnets, dozens of patches of velcro, and then you shook it around … well, the magnets would stick to other magnets, but would they stick to the right magnets?

You might imagine that there are many ways the protein could fold. But there’s only a single final shape that would allow the protein to function correctly in a cell.

So your cells use little helpers to ensure that proteins fold correctly. Some of the helpers are called “molecular chaperones,” and they guard various parts of the long strand so that it won’t glom together incorrectly. Some helpers are called “glycosylation enzymes,” and these glue little bits and bobs to the surface of a protein, some of which seem to act like mailing addresses to send the protein to the right place in a cell, some of which change the way the protein folds.

Our cells have a bunch of ways to ensure that each protein folds into the right 3D shape. And even with all this help, something things go awry. Alzheimer’s disease is associated with amyloid plaques that form in the brain – these are big trash heaps of misfolded proteins. The Alzheimer’s protein is just very tricky to fold correctly, especially if there’s a bunch of the misfolded protein strewn about.

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Many human proteins can be made by bacteria. Humans and bacteria are relatives, after all – if you look back in our family trees, you’ll find that humans and bacteria shared a great-great-great-grandmother a mere three billion years ago.

The cookbooks in our cells are written in the same language. Bacteria can read all our recipes.

Which is great news for biochemists, because bacteria are really cheap to grow.

If you need a whole bunch of some human protein, you start by trying to make it in bacteria. First you copy down the recipe – which means using things called “restriction enzymes” to move a sequence of DNA into a plasmid, which is something like a bacterial index card – then you punch holes in some bacteria and let your instructions drift in for them to read.

The bacteria churn out copies of your human protein. Bacteria almost always make the right long rope of amino acids.

But human proteins sometimes fold into the wrong shapes inside bacteria. Bacteria don’t have all the same helper molecules that we do,.

If a protein doesn’t fold into the right shape, it won’t do the right things.

If you were working in a laboratory, and you found out that the protein you’d asked bacteria to make was getting folded wrong … well, you’d probably start to sigh a lot. Instead of making the correctly-folded human protein, your bacteria gave you useless goo.

Shucks.

But fear not!

Yeast can’t be grown as cheaply as bacteria, but they’re still reasonably inexpensive. And yeast are closer relatives – instead of three billion years ago, the most recent great-great-grandmother shared between humans and yeast lived about one billion years ago.

Yeast have a few of the same helper proteins that we do. Some human proteins that can’t be made in bacteria will fold correctly in yeast.

So, you take some yeast, genetically modify it to produce a human protein, then grow a whole bunch of it. This is called “fermentation.” It’s like you’re making beer, almost. Genetically modified beer.

Then you spin your beer inside a centrifuge. This collects all the solid stuff at the bottom of the flask. Then you’ll try to purify the protein that you want away from all the other gunk. Like the yeast itself, and all the proteins that yeast normally make.

If you’re lucky, the human protein you were after will have folded correctly!

If you’re unlucky, the protein will have folded wrong. Your yeast might produce a bunch of useless goo. And then you do more sighing.

There’s another option, but it’s expensive. You can make your human protein inside human cells.

Normally, human cells are hesitant to do too much growing and dividing and replicating. After all, the instructions in our DNA are supposed to produce a body that looks just so – two arms, two eyes, a smile. Once we have cells in the right places, cell division is just supposed to replace the parts of you that have worn out.

Dead skin cells steadily flake from our bodies. New cells constantly replace them.

But sometimes a cell gets too eager to grow. If its DNA loses certain instructions, like the “contact inhibition” that tells cells to stop growing when they get too crowded, a human cell might make many, many copies of itself.

Which is unhelpful. Potentially lethal. A cell that’s too eager to grow is cancer.

Although it’s really, really unhelpful to have cancer cells growing in your body, in a laboratory, cancer cells are prized. Cancer cells are so eager to grow that we might be able to raise them in petri dishes.

Maybe you’ve heard of HeLa cells – this is a cancer cell line that was taken from a Black woman’s body without her consent, and then this cell line was used to produce innumerable medical discoveries, including many that were patented and have brought in huge sums of money, and this woman’s family was not compensated at all, and they’ve suffered huge invasions of their privacy because a lot of their genetic information has been published, again without their consent …

HeLa cells are probably the easiest human cells to grow. And it’s possible to flood them with instructions to make a particular human protein. You can feel quite confident that your human protein will fold correctly.

But it’s way more expensive to grow HeLa cells than yeast. You have to grow them in a single layer in a petri dish. You have to feed them the blood of a baby calf. You have to be very careful while you work or else the cells will get contaminated with bacteria or yeast and die.

If you really must have a whole lot of a human protein, and you can’t make it in bacteria or yeast, then you can do it. But it’ll cost you.

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Vaccination is perhaps the safest, most effective thing that physicians do.

Your immune system quells disease, but it has to learn which shapes inside your body represent danger. Antibodies and immunological memory arise in a process like evolution – random genetic recombination until our defenses can bind to the surface of an intruder. By letting our immune system train in a relatively safe encounter, we boost our odds of later survival.

The molecular workings of our immune systems are still being studied, but the basic principles of inoculation were independently discovered centuries ago by scientists in Africa, India, and China. These scientists’ descendants practiced inoculation against smallpox for hundreds of years before their techniques were adapted by Edward Jenner to create his smallpox vaccine.

If you put a virus into somebody’s body, that person might get sick. So what you want is to put something that looks a lot like the virus into somebody’s body.

One way to make something that looks like the virus, but isn’t, is to take the actual virus and whack it with a hammer. You break it a little. Not so much that it’s unrecognizable, but enough so that it can’t work. Can’t make somebody sick. This is often done with “heat inactivation.”

Heat inactivation can be dangerous, though. If you cook a virus too long, it might fall apart and your immune system learns nothing. If you don’t cook a virus long enough, it might make you sick.

In some of the early smallpox vaccine trials, the “heat inactivated” viruses still made a lot of people very, very sick.

Fewer people got very sick than if they’d been exposed to smallpox virus naturally, but it feels different when you’re injecting something right into somebody’s arm.

We hold vaccines to high standards. Even when we’re vaccinating people against deadly diseases, we expect our vaccines to be very, very safe.

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It’s safer to vaccinate people with things that look like a virus but can’t possibly infect them.

This is why you might want to produce a whole bunch of some specific protein. Why you’d go through that whole rigamarole of testing protein folding in bacteria, yeast, and HeLa cells. Because you’re trying to make a bunch of protein that looks like a virus.

Each virus is a little protein shell. They’re basically delivery drones for nasty bits of genetic material.

If you can make pieces of this protein shell inside bacteria, or in yeast, and then inject those into people, then the people can’t possibly be infected. You’re not injecting people with a whole virus – the delivery drone with its awful recipes inside. Instead, you’re injecting people with just the propeller blades from the drone, or just its empty cargo hold.

These vaccine are missing the genetic material that allow viruses to make copies of themselves. Unlike with a heat inactivated virus, we can’t possibly contract the illness from these vaccines.

This is roughly the strategy used for the HPV vaccine that my father helped develop. Merck’s “Gardasil” uses viral proteins made by yeast, which is a fancy way of saying that Merck purifies part of the virus’s delivery drone away from big batches of genetically-modified beer.

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We have a lot of practice making vaccines from purified protein.

Even so, it’s a long, difficult, expensive process. You have to identify which part of the virus is often recognized by our immune systems. You have to find a way to produce a lot of this correctly-folded protein. You have to purify this protein away from everything else made by your bacteria or yeast or HeLa cells.

The Covid-19 vaccines bypass all that.

In a way, these are vaccines for lazy people. Instead of finding a way to make a whole bunch of viral protein, then purify it, then put it into somebody’s arm … well, what if we just asked the patient’s arm to make the viral protein on its own?

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Several of the Covid-19 vaccines are made with mRNA molecules.

These mRNA molecules are the index cards that we use for recipes in our cells’ kitchens, so the only trick is to deliver a bunch of mRNA with a recipe for part of the Covid-19 virus. Then our immune system can learn that anything with that particular shape is bad and ought to be destroyed.

After learning to recognize one part of the virus delivery drone, we’ll be able to stop the real thing.

We can’t vaccinate people by injecting just the mRNA, though, because our bodies have lots of ways to destroy RNA molecules. After all, you wouldn’t want to cook from the recipe from any old index card that you’d found in the street. Maybe somebody copied a recipe from The Anarchist Cookbook – you’d accidentally whip up a bomb instead of a delicious cake.

I used to share laboratory space with people who studied RNA, and they were intensely paranoid about cleaning. They’d always wear gloves, they’d wipe down every surface many times each day. Not to protect themselves, but to ensure that all the RNA-destroying enzymes that our bodies naturally produce wouldn’t ruin their experiments.

mRNA is finicky and unstable. And our bodies intentionally destroy stray recipes.

So to make a vaccine, you have to wrap the mRNA in a little envelope. That way, your cells might receive the recipe before it’s destroyed. In this case, the envelope is called a “lipid nanoparticle,” but you could also call a fat bubble. Not a bubble that’s rotund – a tiny sphere made of fat.

Fat bubbles are used throughout cells. When the neurons in your brain communicate, they burst open fat bubbles full of neurotransmitters and scatter the contents. When stuff found outside a cell needs to be destroyed, it’s bundled into fat bubbles and sent to a cellular trash factories called lysosomes.

For my Ph.D. thesis, I studied the postmarking system for fat bubbles. How fat bubbles get addressed in order to be sent to the right places.

Sure, I made my work sound fancier when I gave my thesis defense, but that’s really what I was doing.

Anyway, after we inject someone with an mRNA vaccine, the fat bubble with the mRNA gets bundled up and taken into some of their cells, and this tricks those cells into following the mRNA recipe and making a protein from the Covid-19 virus.

This mRNA recipe won’t teach the cells how to make a whole virus — that would be dangerous! That’s what happens during a Covid-19 infection – your cells get the virus’s whole damn cookbook and they make the entire delivery drone and more cookbooks to put inside and then these spread through your body and pull the same trick on more and more of your cells. A single unstopped delivery drone can trick your cells into building a whole fleet of them and infecting cells throughout your body.

Instead, the mRNA recipe we use for the vaccine has only a small portion of the Covid-19 genome, just enough for your cells to make part of the delivery drone and learn to recognize it as a threat.

And this recipe never visits the nucleus, which is the main library in your cells that holds your DNA, the master cookbook with recipes for every protein in your body. Your cells are tricked into following recipes scribbled onto the vaccine’s index cards, but your master cookbook remains unchanged. And, just like all the mRNA index cards that our bodies normally produce, the mRNA from the vaccine soon gets destroyed. All those stray index cards, chucked unceremoniously into the recycling bin.

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The Johnson & Johnson vaccine also tricks our cells into making a piece of the Covid-19 virus.

This vaccine uses a different virus’s delivery drone to send the recipe for a piece of Covid-19 into your cells. The vaccine’s delivery drone isn’t a real virus – the recipe it holds doesn’t include the instructions on how to make copies of itself. But the vaccine’s delivery drone looks an awful lot like a virus, which means it’s easier to work with than the mRNA vaccines.

Those little engineered fat bubbles are finicky. And mRNA is finicky. But the Johnson & Johnson vaccine uses a delivery drone that was optimized through natural selection out in the real world. It evolved to be stable enough to make us sick.

Now we can steal its design in an effort to keep people well.

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Lots of people received the Johnson & Johnson vaccine without incident, but we’ve temporarily stopped giving it to people. Blood clots are really scary.

You might want to read Alexandra Lahav’s excellent essay, “Medicine Is Made for Men.” Lahav describes the many ways in which a lack of diversity in science, technology, and engineering fields can cause harm.

Cars are designed to protect men: for many years, we used only crash test dummies that were shaped like men to determine whether cars were safe. In equivalent accidents, women are more likely to die, because, lo and behold, their bodies are often shaped differently.

Women are also more likely to be killed by medication. Safety testing often fails to account for women’s hormonal cycles, or complications from contraceptives, or differences in metabolism, or several other important features of women’s bodies.

White male bodies are considered to be human bodies, and any deviation is considered an abnormal case. Medication tested in white men can be approved for everyone; medication tested in Black patients was approved only for use in other Black patients.

Although more than half our population are women, their bodies are treated as bizarre.

For most people, the Johnson & Johnson vaccine is safe. But this is a sort of tragedy that occurs too often – causing harm to women because we’re inattentive to the unique features of their bodies.

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I haven’t been vaccinated yet, but I registered as soon as I was able – my first dose will be on April 26th. Although I’ve almost certainly already had Covid-19 before, and am unlikely to get severely ill the next time I contract it, I’m getting the vaccine to protect my friends and neighbors.

So should you.

On cooperation and cons: Our theft from young people.

On cooperation and cons: Our theft from young people.

As a society, we’ve made enormous sacrifices during the Covid-19 pandemic. We’re wearing masks; we’re staying home; children are missing school.

We’re all cooperating to protect the people who are most at risk.

The risk profile for Covid-19 is opposite the risk from climate change. Covid-19 is more dangerous for the old. Climate change is more dangerous for the young, and for generations not yet born.

There’s another way to phrase this – Covid-19 is more dangerous for the wealthy, and climate change is more dangerous for those who currently have little or nothing. This is true both temporally and geographically.

(Wealth obviously protect individuals from Covid-19. Despite all his buffoonish posturing, when Donald Trump was infected, he received higher quality, more expensive medical care than almost anyone else. But on a population level, increased wealth is correlated with increased risk. Wealthy people are privileged to live longer, and in our capitalist society, people often accumulate wealth as they age.)

People with low risk from Covid-19 are making enormous sacrifices to protect others from it. But those with low risk from climate change are, in general, making no efforts to stop it.

Which conveys a clear message:

Younger people, you must solve this problem on your own. Despite your willingness to make sacrifices to protect us, we will not make sacrifices to protect you.

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If we knew in March 2020 what we know now, we wouldn’t have closed schools. If you’re interested in some of the reasoning behind this, you should read this February 24, 2021 New York Times editorial from Nicholas Kristof.

Or, if you’re more scientifically inclined, you could read this February 23, 2021 review article in The BMJ: “Closing schools is not evidence based and harms children.”

We are hurting kids under the guise of protecting older people. But we’re not even succeeding. Schools have such low rates of Covid-19 transmission that we’re hurting kids without accomplishing anything.

People from “my” political party have orchestrated this harm, which makes it feel all the worse.

The New York Times recently printed an editorial from someone at the right-wing American Enterprise Institute chiding us for our totally un-scientific school closures. Members of the Republican party are positioning themselves as the defenders of public education.

The Republican party has been trying to undermine public schools ever since the Supreme Court decided that maybe Black kids deserve an equal chance to learn. And we’re letting them posture as the defenders of education?

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During the vaccine roll-out, the New York Times set the stage for a big reveal – younger people were never in huge amounts of danger from Covid-19.

I don’t want to sound cavalier about this – Covid-19 is dangerous to people of all ages. It’s very similar to influenza.

Many people have a misconception that influenza is relatively harmless – sniffles & a runny nose – unless you’re elderly.

That’s not true.

Although the majority of cases of seasonal influenza are mild, it’s a deadly disease. Young healthy people die of influenza every year.

Most influenza deaths are recorded as “pneumonia” during post-mortem reports. To compare the dangers of Covid-19 to influenza, we’d want to measure how many more pneumonia deaths we’ve seen recently.

In a typical year, there are about 130,000 pneumonia deaths in the United States – these might be caused by influenza, coronaviruses, rhinoviruses, etc.

Many if not most of these deaths are caused by influenza – the column of numbers reporting verified influenza deaths is so low because we don’t always test for it, and when we do we typically use a low-quality antigen test.

Last year, though, was much worse – between January 1, 2020 and February 24, 2021, there were 670,000 pneumonia deaths in the United States. During those 14 months, five-fold more people died from this set of symptoms than we’d expect during a normal year.

We’ve also had about five times as many infections. Usually, about 30 million people contract seasonal influenza each year. The CDC estimates that perhaps 100 million people contracted Covid-19 during the ten months from February 2020 to December 2020.

That’s why the CDC’s rough estimates for the “infection fatality ratio” of Covid-19 are about the same as for influenza.

Last year, more people died from Covid-19 than would be expected from a typical year’s burden of seasonal influenza, but that’s because there were many more infections.

Seasonal influenza and Covid-19 are both deadly diseases. And it’s worth comparing them because the pandemic might be declared “over” once Covid-19 deaths fall to influenza-like levels.

That’s what most public health experts said when they were interviewed by Alexis Madrigal for an article in The Atlantic – that a reasonable goal is for Covid-19 “to mirror the typical mortality of influenza in the U.S. over a typical year.”

Which seems like a bit of a cop out. You’re going to call it “over” while people are still dying?

But we have to. Covid-19 will probably be with us forever. Like the coronavirus OC43, which we picked up from cows and which probably killed over a million people during the 1890 pandemic, Covid-19 will continue to make humans sick indefinitely.

Elderly people – especially those who weren’t exposed to Covid-19 as children – will always be particularly susceptible.

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Early on during the pandemic – when we already had a good sense that younger people weren’t in much personal danger but also knew that we could only slow the spread of Covid-19 if younger people made sacrifices – we concocted a narrative that healthy young people were at high risk, too.

In March 2020, the New York Times printed an editorial from Fiona Lowenstein, a 26 year old who became tragically ill, saying “Millennials: if you can’t stay at home for others, do it for yourselves.”

In May 2020, the New York Times printed an editorial from Mara Gay, a 33 year old who became tragically ill, saying “I want Americans to understand that this virus is making otherwise young, healthy people very, very sick. I want them to know, this is no flu.”

During a “mild” flu season, about 1,000 people aged 25-34 die of pneumonia.

This year, healthy young people have gotten very sick and even died of Covid-19 – which is tragic, but not unusual. Every year, healthy young people get very sick and die from influenza. This past year, with about five-fold more infections of an equivalently deadly disease, we’ve seen about five-fold more of these tragic young people’s deaths.

Now that a vaccine is available, though, the narrative has shifted.

In the February 28, 2021 New York Times Magazine, Kwame Anthony Appiah’s “Ethicist” column says that “Health care workers who are in their 20s and don’t have certain medical conditions aren’t at high risk if they contract Covid-19. Perhaps we could save more lives if we left them [to be vaccinated] until later.”

Now that we have a limited supply of vaccines, older, wealthier people benefit if young people are less afraid of Covid-19.

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By delaying Covid-19 infection, young people increased their personal risk. Early during the pandemic, the virus was not particularly dangerous for young people. By now, though, there have now been millions of transmission events – millions of opportunities for mutant variants to arise.

And indeed, in February 2021 the New York Times reports that “it is likely that the [new Covid-19 virus] variant is linked to an increased risk of hospitalization and death.”

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Currently, we’re rationing the limited supply of Covid-19 vaccines based on age.

This is hypocritical, and potentially misguided.

When people develop such severe complications from Covid-19 that they require ventilation in order to have a chance of surviving, a younger person is more likely to benefit from the treatment. This holds both in terms of absolute number of lives saved, and is even more dramatic if you consider the years of life saved.

With a limited supply of ventilators, you can accomplish most by reserving them for the young – and we said that would be horrible.

In a March 2020 article for the New York Times, Sheri Fink wrote that the health department’s civil rights office would ensure “that states did not allow medical providers to discriminate on the basis of … age … when deciding who would receive lifesaving medical care.

In April 2020, Joel Zivot wrote for Medpage that “Rationing ventilators by age is wrong.”

Although we declared that it would be unethical to ration healthcare (ventilators) by age, we’re now rationing healthcare (vaccines) by age. The difference is that a different group of people – older, on average wealthier – benefits.

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Rationing vaccines by age doesn’t even save the most lives.

Based on the CDC data, if both a 50-year-old and a 70-year-old are infected with Covid-19, the 70-year-old is about ten times more likely to die. That’s scary!

The major benefit of the vaccine is that it reduces the chance of severe illness if you are exposed to Covid-19. But we also know other ways to reduce the odds of exposure – a person can stay home, wear a mask near others, minimize the number of unique individuals they come into contact with.

If the 70-year-old has retired, they should be able to reduce the number of unique individuals they see each week to ten or fewer. But a 50-year-old grocery store clerk might see a thousand or more unique individuals each week, and have to spend time in fairly close proximity to each.

If the 50-year-old is at least ten-fold more likely to be exposed to Covid-19, then you’ll save more lives by giving the vaccine to them instead of to the 70-year-old.

Not only did we declare that rationing healthcare by age was wrong when it benefited younger people, but now we’re doing it even though it doesn’t save the most lives.

The unfairness is even more dramatic if we consider the risk of hospitalization. According to the CDC chart above, if both a 20-year-old and a 70-year-old are infected with Covid-19, the 70-year-old is about five times as likely to be hospitalized. But Medicare will pay the hospital bill. If a 20-year-old is hospitalized, they might face ruinous medical debt.

It’s quite likely that the obligations of most 20-year-olds – going to school, going to work, taking care of family – make them at least five times as likely to be exposed to Covid-19. We could stop lives from being ruined by medical debt if we vaccinated 20-year-olds first.

A friend of mine works in a take-out & delivery pizza restaurant in Chicago. For other people to be able to stay home and order food, he had to go in to work. His risk of exposure to Covid-19 was much higher than other people’s. As a healthy athlete in his late twenties, he wasn’t at high risk, but he was unlucky – when he got sick, he was so ill that he spent weeks in the hospital. He’s still recovering from his ruptured lung. He has no idea how to pay the $200,000 medical bill.

Because we’re rationing care by age, we’re not protecting people like him. Even though his risk – interacting with customers all day – made it possible for others to stay safe.

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The Covid-19 pandemic has been awful, but I was pleased that people took fewer plane flights. Our carbon emissions briefly dropped.

Now that older people have received vaccines, though, they’ll resume flying.

For a February 17, 2021 article in the New York Times, Debra Kamin writes that “When the coronavirus hit, Jim and Cheryl Drayer, 69 and 72, canceled all their planned travel and hunkered down in their home in Dallas, Texas. But earlier this month, the Drayers both received the second dose of their Covid-19 vaccinations. And in March, armed with their new antibodies, they are heading to Maui for a long overdue vacation.”

“Americans over 65, who have had priority access to inoculations, are now newly emboldened to travel – often while their children and grandchildren continue to wait for a vaccine.”

Newly protected against Covid-19, they’ll increase their contributions to climate change.

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Climate change has the opposite risk profile from Covid-19. Covid-19 is most dangerous for the old; climate change is most dangerous for the young, and for generations not yet born.

In some sense, it’s trivializing to even compare these. The risk from climate change is so much more severe.

If we make our planet inhospitable – if our crops fail due to storms or heat waves – the carrying capacity of Earth could easily fall by half.

We will see billions, not millions, of deaths.

Someone who is elderly today is unlikely to survive long enough to experience the worst effects of climate change – although it’s true that in severe weather events like Chicago’s fluke summer heat waves or Texas’s fluke winter storms, elderly people who live alone are exceptionally vulnerable.

Still, younger adults will have to endure worse calamities. They’ll live through more years of severe weather, crop failures, dangerous heat, lingering smog. And, since society will be forced to spend more money each year to maintain humanity’s precarious place on this planet – rebuilding after fires or floods – younger adults will face an increasingly inhospitable world with less wealth at their disposal.

Today’s children will encounter even worse. They’ll experience every disaster that today’s young adults will survive to see, and then some.

Generations not yet born may inherit a nightmare.

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When people who currently have wealth were in danger, we created a narrative that everyone needed to make sacrifices. The largest sacrifices came from those who benefited least.

We’re still keeping children out of school – for almost no benefit in terms of Covid-19 transmission – in order to protect older, wealthier people.

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Climate change is and has been caused primarily by those with the most wealth. If you can buy more meat, if you can take more plane flights, if you can purchase a bigger home, then you’re able to cause more climate change.

To stop climate change, we need wealthy people to make sacrifices. Buy less, fly less, eat plants.

But why would they?

Currently wealthy people aren’t in danger.

And – worse – currently wealthy people often became wealthy by treating the world as a competitive place. Now we’re asking them to cooperate? To make sacrifices for the sake of others?

Meat tastes good. Flying to Maui is fun. Doesn’t a person who worked hard deserve an enormous home?

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A curious thought about the Gamestop stock trading phenomenon: Many small investors – often younger people – were convinced through emotional arguments to buy a few shares of stock and hold them with “diamond hands.”

Don’t sell, even if the price dips!

There was a strange cooperative / competitive system going on. The cooperative portion would have been illegal had it not been done in public – people were colluding to make the shares hard to get, which forced the hedge fund to pay more in order to cover their short sales.

Short sales: a hedge fund had borrowed many shares of the stock and sold them, hoping the price would fall and that new shares could be purchased more cheaply when it was time to return them. So the hedge fund had basically announced, “On such & such a date, I must have this stock, no matter the price!” If other people all cooperate and say, “On that day, don’t sell it for less than $420.00,” then the hedge fund has to pay $420.00 per share, even if the company that the stock represents is worthless.

But here’s the competitive portion – the company, Gamestop, is probably going out of business eventually. Driving to a strip mall to buy a video game cartridge instead of downloading it? The stock isn’t worth much money. So people wanted to cooperate to hurt the hedge fund, but people were also forced to compete because nobody wanted to be holding the stock at the end of the day.

Everyone would like to sell it for a bunch of money, but not everyone will get to sell it.

Even if more than a hundred percent of shares are short sold, not everyone will get to sell it – the hedge fund can satisfy all their contracts by buying a share, returning it to someone, buying the same share back from that person, returning it to someone else, and so on.

So if you know that everybody else has put in a “sell order” at $420.00, because they think it’s a funny number, you benefit by putting in a sell order at $419. That way you get almost as much money as anyone else, but you’re guaranteed to sell yours, whereas only a fraction of the people with $420 sell orders get to trade their (worthless) stock for money.

But then, if you know that other people are going to plug in a sell order at $419, you benefit from selling yours at $418. Because what if too many people sell their shares at $419?? You might still be left out!

So there was an incentive for savvy investors – wealthy people who might have thousands of dollars on the line – to convince other people to hold onto the stock no matter what … even while selling their own.

Billions of dollars changed hands. Some people “made” a lot of money. And it wouldn’t have happened without cooperation – lots of people colluding against the hedge fund.

But the particular people who benefited were determined by a con. By selling shares while promoting a narrative that “if we all hold with diamond hands, this is going to the moon!”

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In some ways, our response to Covid-19 encourages me.

So many people – especially younger people – have shown themselves to be willing to cooperate.

A cloth mask traps your exhalations. Wearing a cloth mask makes your life worse, but it protects other people. Almost everybody in my home town wears a mask. Every young person at school wears a mask.

And yet.

Young people are willing to make sacrifices to protect older people. But therein lies the con.

We’re not making sacrifices to protect them.

Our carbon emissions are no different from pulling off this face mask and intentionally coughing in a young child’s face. We ought to feel ashamed.

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header image from Socialist Appeal on flickr

On complexity and seemingly good ideas.

On complexity and seemingly good ideas.

Elizabeth Kolbert’s lovely essay in the New York Review of Books, “Chemical Warfare’s Home Front,” describes Fritz Haber’s contribution to the use of toxic gas in war.

Haber orchestrated the use of chlorine to suffocate all animal life – including soldiers – downwind of his nation’s troops. And his plan succeeded. After unleashing 300,000 pounds of chlorine gas, huge numbers of people died. Soldiers– some of whom suffocated, some whose lungs burned, some who committed suicide when enveloped by the gas – as well as horses, cows, chickens, wildlife.

Chemical warfare is horrible, but Haber’s battlefield “experiment” was considered a success. Military researchers then concocted more dangerous chemical agents, like DNA-crosslinking mustard gas and muscle-clenching Sarin nerve gas.

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Fritz Haber’s other ideas were seemingly more beneficial for humanity. Haber was awarded the Nobel Prize in chemistry for making synthetic fertilizer.

Synthetic fertilizer let us grow more crops.

We could feed billions more people!

The global population soared.

If we hadn’t invented synthetic fertilizer, the global population would still be under four billion people.

Climate change would still be a huge problem – the most outrageous polluters haven’t been the most populous nations. Climate change was caused primarily by the United States and other wealthy nations, whereas overpopulation will first devastate equatorial nations.

A seemingly good idea – more fertilizer! – has greatly exacerbated the scale of suffering.

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Kolbert discusses the invention of chlorofluorocarbons, which seemed like great coolants. With CFCs, Frigidaire could build cheaper refrigerators! Regular families could keep their ice cream cold without spending as much on electricity.

Unfortunately, CFCs also dissolve our ozone layer. More dangerous ultraviolet radiation began to reach us from the sun, causing horrible skin cancers.

CFCs seemed like a good idea — they do work great as coolants — but they caused awful problems as part of a bigger system.

Kolbert quotes the chemist F. Sherwood Rowland, who said, in reference to his studies of CFCs, “The work is going very well, but it looks like the end of the world.”

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Anthropologist Joseph Tainter argued civilizations collapse when overwhelmed by complexity.

Like the children’s nursery rhyme about the old lady who swallowed a fly — then a spider to catch the fly, then a cat to catch the spider — our complicated solutions can create new, perhaps worse, problems.

This is the theme of Jenny Kleeman’s Sex Robots and Vegan Meat. Kleeman investigates several industries that purport to solve our world’s problems – You can eat meat without killing animals! You can make a baby without a mother’s body! – without addressing the fundamental causes of these problems.

Describing her travels, Kleeman writes:

I head back to my hotel as the reassuring cloak of darkness falls on Las Vegas. I’m exhausted. Music is thumping out of huge speakers mounted on the building’s exterior: throbbing, pounding beats that are supposed to entice gamblers into the hotel’s casino. I wipe my key card and flop down on the giant bed.

On the bedside table, there’s a metal dish full of individually wrapped pairs of earplugs: wax ones, foam ones, silicone ones – a profusion of solutions supplied by the management to the noise pollution problem caused by the management.

They could just switch the music off, of course, but they have provided a little piece of technology instead so they don’t have to.

My head is full of Eva, [a prototype interactive sex doll] who has the body of a real woman, but can be beaten without feeling a thing. Rather than dealing with the cause of a problem, we invent something to try to cancel it out.

Perhaps we should eat different foods. Perhaps our attitudes about sex or the importance of a sociable community are making our lives worse. Perhaps if we addressed these issues directly, we wouldn’t need sex robots or vegan meat.

Clean meat is one of many possible futures of food, so long as we continue to eat meat. We will always have the power to not want it anymore, or to want it much less.

That is where the real power lies: in harnessing our desires, rather than in mastering technology. Until we do, we will be even further removed from where our food comes from, and will feel even less responsible for it.

We will be perpetuating the kind of thinking that caused the meat mess in the first place.

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In April 2020, I described two major drawbacks to our efforts to “slow the spread” of Covid-19 instead of providing targeted protection for the people at high risk of severe illness.

1.) Immunity to most coronaviruses lapses within a matter of months. Keeping the virus in circulation longer increases the total number of infections and makes it more difficult to shield people at high risk from eventual exposure.

2.) Each infection encompasses some number of viral replications and thus genetic drift. If a population of 20 people transfers a virus between themselves one by one, rather than all catching it from the same initial carrier, the virus has 20-fold more generations to mutate and better evade our immune systems.

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Admittedly, my April 2020 prediction about the timeline for vaccine development was quite wrong – I thought this might take three to five years. I’m thankful that I was wrong. I’m obviously grateful for the fantastic work done by vaccine developers so far.

For these vaccines to effectively staunch viral transmission, we’ll need to vaccinate large numbers of people – immunity from prior infections won’t necessarily help much because immunity to this particular virus lapses so quickly, and because people’s prior infections were staggered in time. (Indeed, we’ll probably need to vaccinate large numbers of people repeatedly, because some of our data suggests that vaccine-derived immunity to this also lapses on a timescale of months.)

Unfortunately, we live in a country where large numbers of people distrust the medical establishment. Even if we had sufficient doses of the vaccines available today, I don’t know what percentage of our population would choose to get them.

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Masks definitely reduce viral transmission. It was obviously a good idea for everyone to wear masks anywhere that high risk and lower risk people share the same space.

Cooperation definitely makes for a better place to live. In places that enacted mask orders, it’s obviously a good idea to follow them.

It’s worth remembering, though, that any fix – even something as simple as this piece of cloth covering my nose and mouth – can have unintentional consequences. New virus variants – which our current vaccines may be less effective against – are a predictable result of our effort to “slow the spread” with masks.

And yet.

I volunteer with Pages to Prisoners, an organization that sends free books to people who are incarcerated. We’ve included a sheet of information about Covid-19 with each package recently, helping to explain that Covid-19 is not a hoax, that it’s a dangerous respiratory disease, that masks and social distancing can help people reduce their risk.

I’m currently revising this information sheet – it was put together months ago, when we understood less about this virus – and I’m still recommend that everyone wear masks.

Not just because prisons are places where many low risk and high risk people are confined together — although, they are. Outrageous sentencing practices have led to a large number of elderly people being stuck in prison.

But also, anecdotal evidence suggests that people are more likely to develop severe illness from Covid-19 when they are exposed to a large number of viral particles at once.

Viruses reproduce exponentially – you can get sick if you inhale even one capsid. But you’re more likely to get seriously ill if you inhale a whole bunch of viral particles. If you’re initially exposed to a small number of particles, your body will have more time to fight off the infection before it makes you feel sick.

Research studies from military bases have shown that Covid-19 will continue to spread even when everyone wears masks and tries to stay six feet away from each other. But we haven’t tested – an experiment like this would be totally unethical – whether we’re more likely to see asymptomatic or mild cases when people’s initial exposure is to a small number of viral particles.

It’s quite likely, though.

So, although I think our efforts to “slow the spread” weren’t the best plan last year, I’ll still be recommending masks.

On reinfection.

On reinfection.

If you’ve been reading about Covid-19 in the New York Times, you’ve probably learned that reinfection is very unlikely.

What you’ve learned is incorrect.

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Don’t get me wrong – I love the New York Times. Within the spectrum of United States politics, I am very far to the left. Anti-consumerist, prison abolitionist, environmentalist, feminist, climate activist, etc., etc. I fit into all those categories.

I’m also a scientist. I am staunchly pro-vaccine. I don’t like pesticides, but I’m a huge fan of GMO crops. (Honestly, I wish there was a category at the grocery store where you could pay to support genetically-modified organisms grown without environmental toxins – “organic” doesn’t have the nuance I’d like.)

So my goal here isn’t to rag on the New York Times. I’m including screenshots of their headlines only to give us a common frame of reference.

This is what the news is saying. And it’s wrong.

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It was going to be very difficult to demonstrate reinfection with Covid-19.

Why?

In general, reinfection with any virus will produce a milder illness the second time.

Most people’s first infection with Covid-19 is so mild that they don’t realize they have it – perhaps 80% of infections are “asymptomatic,” in which a person has been infected with the virus, is probably shedding the virus (thereby infecting other people), but feels totally fine. So, people’s second infection? Some percentage higher than 80% are likely to feel totally well, even though they might be shedding virus.

When people develop severe complications from Covid-19, the illness can linger for weeks or even months.

I don’t know for certain whether my family contracted Covid-19 in February, because there were no tests available here at the time. All I know is that we were two close contacts removed from someone who had just returned from China, that this close contact tested negative for influenza, that my family had been vaccinated for influenza, and that our symptoms precisely mirrored the common suite for Covid-19. But in any case, we felt horrible for about three weeks, and we experienced lingering fatigue with occasional coughing for about two months.

Lengthy recovery is so common that there’s a colloquial name for it: “long-haulers.” If we’re trying to identify whether someone was re-infected, we’d need to make sure that we weren’t looking at continued viral shedding during a lengthy recovery.

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To demonstrate that someone was re-infected with Covid-19, the following would have to happen:

  • A person gets tested for Covid-19 during their first infection.
  • The genome of the virus is sequenced after that first infection.
  • The person is re-infected.
  • The person happens to get a Covid-19 test during the second infection (even though it’s highly likely that this person feels well at the time).
  • The genome of the virus is sequenced after the second infection.
  • The genome of the virus that infected the person on the second occasion is noticeably different from the first (even though Covid-19 includes a proofreading enzyme that slows genetic drift).

That’s all very unlikely!

There are just so many coincidences involved – that you happen to get infected with an easily distinguishable virus the second time, that you happen to get a test the second time, that anyone took the (significant) trouble and expense to sequence both genomes.

And what I mean is, proving re-infection is very unlikely. Which is totally independent of the likelihood of re-infection itself.

And yet, even though it’s so unlikely we’d be able to prove that re-infection is occurring, we have.

We know, with 100% certainty, that people can be reinfected. We’ve documented it.

Given how unlikely it was that we’d be able to document reinfection, the fact that we’ve seen this at all indicates that it’s probably quite common. As you would expect based upon our bodies’ responses to other coronaviruses.

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Given that re-infection definitely occurs, and is probably quite common, why have you read that it’s unlikely?

The underlying probably is language usage. When my father – an infectious diseases specialist – talks about re-infection, he’s thinking about contracting severe symptoms during a second infection. Which is reasonable. He’s a medical doctor. He cares about helping sick people get better.

But when we’re thinking about how to respond, as a nation, to this pandemic, we’re thinking about the dynamics of transmission. We’re trying to answer questions like, “Can kids go to school without people dying?”

(Yup, they can! And should!)

From this perspective, we’re thinking about who is going to spread the virus, and where. We need to know whether a person who is protected from severe disease – either from prior recovery or vaccination – might shed viral particles. Will that individual register as a positive case on a PCR test? Will that individual get classmates or co-workers sick?

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Re-infections are probably the underlying cause of the current rise in cases in New York City.

70% or more of the population of New York City was infected with Covid-19 during April. That’s a huge percentage, well above what most researchers consider the “herd immunity threshold” for similar respiratory viruses.

For there to be another spike in cases now, many of those 70% would need to have lost their initial immunity. That’s also why you’d expect to see a higher “test positivity rate” – if many of the current cases are reinfections, then they’re likely to be milder. People with milder (or asymptomatic) infections are less likely to seek out a test.

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For general audiences, the phrasing I’d recommend is to say “Severe illness is unlikely during Covid-19 reinfections” as opposed to “Reinfection is unlikely.”

There have been a few cases of people’s second infection being more severe than the first, but these cases indeed appear to be quite rare.

But re-infection itself?

The fact that we’ve documented any instances of re-infection suggests that it’s quite common. Which we could have predicted from the beginning – indeed, I did. And that’s why I’ve been recommending – for months – policies very different from what we’ve done.

On predictions and a scientific response to calamity.

On predictions and a scientific response to calamity.

We’re fast approaching flu season, which is especially harrowing this year.

We, as a people, have struggled to respond to this calamity. We have a lot of scientific data about Covid-19 now, but science is never value-neutral. The way we design experiments reflects our biases; the way we report our findings, even more so.

For example, many people know the history of Edward Jenner inventing the world’s first vaccine. Fewer are aware of the long history of inoculation in Africa (essentially, low-tech vaccination) that preceded Jenner’s work.

So it’s worthwhile taking a moment to consider the current data on Covid-19.

Data alone can’t tell us what to do – the course of action we choose will reflect our values as a society. But the data may surprise a lot of people – which is strange considering how much we all feel that we know about Covid-19.

Indeed, we may realize that our response so far goes against our professed values.

Spoiler: I think we shouldn’t close in-person school.

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Since April, I’ve written several essays about Covid-19. In these, I’ve made a number of predictions. It’s worthwhile to consider how accurate these predictions have been.

This, after all, is what science is. We use data to make an informed prediction, and then we collect more data to evaluate how good our prediction was.

Without the second step – a reckoning with our success or failure – we’re just slinging bullshit.

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I predicted that our PCR tests were missing most Covid-19 infections, that people’s immunity was likely to be short-lived (lasting for months, not years), and that Covid-19 was less dangerous than seasonal influenza for young people.

These predictions have turned out to be correct.

In my essays, I’ve tried to unpack the implications of each of these. From the vantage of the present, with much more data at our disposal, I still stand by what I’ve written.

But gloating’s no fun. So I’d rather start with what I got wrong.

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My initial predictions about Covid-19 were terrible.

I didn’t articulate my beliefs at the time, but they can be inferred from my actions. In December, January, and February, I made absolutely no changes to my usual life. I didn’t recommend that travelers be quarantined. I didn’t care enough to even follow the news, aside from a cursory glance at the headlines.

While volunteering with the high school running team, I was jogging with a young man who was finishing up his EMT training.

“That new coronavirus is really scary,” he said. “There’s no immunity, and there’s no cure for it.”

I shrugged. I didn’t know anything about the new coronavirus. I talked with him about the 1918 influenza epidemic instead.

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I didn’t make any change in my life until mid-March. And even then, what did I do?

I called my brother and talked to him about the pizza restaurant – he needed a plan in case there was no in-person dining for a few months.

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My next set of predictions were off, but in the other direction – I estimated that Covid-19 was about four-fold more dangerous than seasonal influenza. The current best estimate from the CDC is that Covid-19 is about twice as dangerous, with an infection fatality ratio of 0.25%.

But seasonal influenza typically infects a tenth of our population, or less.

We’re unlikely to see a significant disruption in the transmission of Covid-19 (this is the concept of “herd immunity”) until about 50% of our population has immunity from it, whether from vaccination or recovery. Or possibly higher – in some densely populated areas, Covid-19 has spread until 70% (in NYC) or even 90% (in prisons) of people have contracted the disease.

Population density is hugely important for the dynamics of Covid-19’s spread, so it’s difficult to predict a nation-wide threshold for herd immunity. For a ballpark estimate, we could calculate what we’d see with a herd immunity threshold of about 40% in rural areas and 60% in urban areas.

Plugging in some numbers, 330 million people, 80% urban population, 0.25% IFR, 60% herd immunity threshold in urban areas, we’d anticipate 450,000 deaths.

That’s about half of what I predicted. And you know what? That’s awful.

Each of those 450,000 is a person. Someone with friends and family. And “slow the spread” doesn’t help them, it just stretches our grieving to encompass a whole year of tragedy instead of a horrific month of tragedy.

If we don’t have a safe, effective vaccine soon enough, the only way to save some of those 450,000 people is to shift the demographics of exposure.

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Based on the initial data, I concluded that the age demographics for Covid-19 risk were skewed more heavily toward elderly people than influenza risk.

I may have been wrong.

It’s difficult to directly compare the dangers of influenza to the dangers of Covid-19. Both are deadly diseases. Both result in hospitalizations and death. Both are more dangerous for elderly or immunocompromised people, but both also kill young, healthy people.

Typically, we use an antigen test for influenza and a PCR-based test for Covid-19. The PCR test is significantly more sensitive, so it’s easier to determine whether Covid-19 is involved a person’s death. If there are any viral particles in a sample, PCR will detect them. Whereas antigen tests have a much higher “false negative” rate.

Instead of using data from these tests, I looked at the total set of pneumonia deaths. Many different viruses can cause pneumonia symptoms, but the biggest culprits are influenza and, in 2020, Covid-19.

So I used these data to ask a simple question – in 2020, are the people dying of pneumonia disproportionately more elderly than in other years?

I expected that they would be. That is, after all, the prediction from my claims about Covid-19 demographic risks.

I was wrong.

In a normal year (I used the data from 2013, 2014, and 2015, three years with “mild” seasonal influenza), 130,000 people die of flu-like symptoms.

In 2020 (at the time I checked), 330,000 people have died of flu-like symptoms. Almost three times as many people as in a “normal” year.

For people under the age of 18, we’ve seen the same number of deaths (or fewer) in 2020 as in other years. The introduction of Covid-19 appears to have caused no increased risk for these people.

But for people of all other ages, there have been almost three times as many people dying of these symptoms in 2020 compared to other years.

In most years, one thousand people aged 25-34 die of these symptoms; in 2020, three thousand have died. In most years, two thousand people aged 35-44 die of these symptoms; in 2020, six thousand have died. This same ratio holds for all ages above eighteen.

Younger people are at much less risk of harm from Covid-19 than older people are. But, aside from children under the age of eighteen, they don’t seem to be exceptionally protected.

Of course, my predictions about the age skew of risk might be less incorrect than I’m claiming here. If people’s dramatically altered behavior in 2020 has changed the demographics of exposure as compared to other years – which is what we should be doing to save the most lives – then we could see numbers like this even if Covid-19 had the risk skew that I initially predicted.

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I predicted that four or more years would pass before we’d be able to vaccinate significant numbers of people against Covid-19.

I sure hope that I was wrong!

We now know that it should be relatively easy to confer immunity to Covid-19. Infection with other coronaviruses, including those that cause common colds, induce the production of protective antibodies. This may partly explain the low risk for children – because they get exposed to common-cold-causing coronaviruses so often, they may have high levels of protective antibodies all the time.

Several pharmaceutical companies have reported great results for their vaccine trials. Protection rates over 90%.

So the problem facing us now is manufacturing and distributing enough doses. But, honestly, that’s the sort of engineering problem that can easily be addressed by throwing money at it. Totally unlike the problem with HIV vaccines, which is that the basic science isn’t there – we just don’t know how to make a vaccine against HIV. No amount of money thrown at that problem would guarantee wide distribution of an effective vaccine.

We will still have to overcome the (unfortunately significant) hurdle of convincing people to be vaccinated.

For any individual, the risk of Covid-19 is about twice the risk of seasonal influenza. But huge numbers of people choose not to get a flu vaccine each year. In the past, the United States has had a vaccination rate of about 50%. Here’s hoping that this year will be different.

Covid-19 spreads so fast – and so silently, with many cases of infected people who feel fine but are still able to spread the virus – that it will almost certainly be a permanent resident of the world we live in. We’re unlikely to eradicate Covid-19.

Which means that elderly people will always be at risk of dying from Covid-19.

The only way to protect people whose bodies have gone through “age-related immunosenence” – the inevitable weakening of an immune system after a person passes the evolutionarily-determined natural human lifespan of about 75 years – will be to vaccinate everybody else.

Depending on how long vaccine-conferred immunity lasts, we may need to vaccinate people annually. I worry, though, that it will become increasingly difficult to persuade people to get a Covid-19 vaccine once the yearly death toll drops to influenza-like levels – 50,000 to 100,000 deaths per year in the United States.

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I wrote, repeatedly, that immunity to Covid-19 is likely to be short-lived. Immunity to other coronaviruses fades within a few months.

(Note: you may have seen articles in the New York Times suggesting that we’ll have long-lasting protection. They’re addressing a different question — after recovery, or vaccination, are you likely to become severely ill with Covid-19? And the answer is “probably not,” although it’s possible. When I discuss immunity here, I mean “after recovery, or vaccination, are you likely to be able to spread the virus after re-infection?” And the answer is almost certainly “yes, within months.”)

And I wrote about the interplay between short-lived immunity and the transmission dynamics of an extremely virulent, air-born virus.

This is what the Harvard public health team got so wrong. When we slow transmission enough that a virus is still circulating after people’s immunity wanes, they can get sick again.

For this person, the consequences aren’t so dire – an individual is likely to get less sick with each subsequent infection by a virus. But the implications for those who have not yet been exposed are horrible. The virus circulates forever, and people with naive immune systems are always in danger.

It’s the same dynamics as when European voyagers traveled to the Americas. Because the European people’s ancestors lived in unsanitary conditions surrounded by farm animals, they’d cultivated a whole host of zoogenic pathogens (like influenza and this new coronavirus). The Europeans got sick from these viruses often – they’d cough and sneeze, have a runny nose, some inflammation, a headache.

In the Americas, there were fewer endemic diseases. Year by year, people wouldn’t spend much time sick. Which sounds great, honestly – I would love to go a whole year without headaches.

But then the disgusting Europeans reached the Americas. The Europeans coughed and sneezed. The Americans died.

And then the Europeans set about murdering anyone who recovered. Today, descendants of the few survivors are made to feel like second-class citizens in their ancestral homelands.

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In a world with endemic diseases, people who have never been exposed will always be at risk.

That’s why predictions made in venues such as the August New York Times editorial claiming that a six- to eight-week lockdown would stop Covid-19 were so clearly false. They wrote:

Six to eight weeks. That’s how long some of the nation’s leading public health experts say it would take to finally get the United States’ coronavirus epidemic under control.

For proof, look at Germany. Or Thailand. Or France.

Obviously, this didn’t work – in the presence of an endemic pathogen, the lockdowns preserved a large pool of people with naive immune systems, and they allowed enough time to pass that people who’d been sick lost their initial immunity. After a few months of seeming calm, case numbers rose again. For proof, look at Germany. Or France.

Case numbers are currently low in Thailand, but a new outbreak could be seeded at any time.

And the same thing is currently happening in NYC. Seven months after the initial outbreak, immunity has waned; case numbers are rising; people with mild second infections might be spreading the virus to friends or neighbors who weren’t infected previously.

All of which is why I initially thought that universal mask orders were a bad idea.

We’ve known for over a hundred years that masks would slow the spread of a virus. The only question was whether slowing the spread of Covid-19 would cause more people to die of Covid-19.

And it would – if a vaccine was years away.

But we may have vaccines within a year. Which means that I may have been wrong. Again, the dynamics of Covid-19 transmission are still poorly understood – I’ll try to explain some of this below.

In any case, I’ve always complied with our mask orders. I wear a mask – in stores, at school pickup, any time I pass within six feet of people while jogging.

To address global problems like Covid-19 and climate change, we need global consensus. One renegade polluting wantonly, or spewing viral particles into the air, could endanger the whole world. This is precisely the sort of circumstance where personal freedom is less important than community consensus.

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The transmission dynamics of Covid-19 are extremely sensitive to environment. Whether you’re indoors or outdoors. How fast the air is moving. The population density. How close people are standing. Whether they’re wearing masks. Whether they’re shouting or speaking quietly.

Because there are so many variable, we don’t have good data. My father attended a lecture and a colleague (whom he admires) said, “Covid-19 is three-fold more infectious than seasonal influenza.” Which is bullshit – the transmission dynamics are different, so the relative infectivity depends on our behaviors. You can’t make a claim like this.

It’s difficult to measure precisely how well masks are slowing the spread of this virus.

But here’s a good estimate: according to Hsiang et al., the number of cases of Covid-19, left unchecked, might have increased exponentially at a rate of about 34% per day in the United States.

That’s fast. If about 1% of the population was infected, it could spread to everyone within a week or two. In NYC, Covid-19 appear to spread to over 70% of the population within about a month.

(To estimate the number of infections in New York City, I’m looking at the number of people who died and dividing by 0.004 – this is much higher than the infection fatality rate eventually reported by the CDC, but early in the epidemic, we were treating people with hydroxychloraquine, an unhelpful poison, and rushing to put people on ventilators. We now know that ventilation is so dangerous that it should only be used as a last resort, and that a much more effective therapy is to ask people to lie on their stomachs – “proning” makes it easier to get enough oxygen even when the virus has weakened a person’s lungs.)

Masks dramatically slow the rate of transmission.

A study conducted at a military college – where full-time mask-wearing and social distancing were strictly enforced – showed that the number of cases increased from 1% to 3% of the population over the course of two weeks.

So, some math! Solve by taking ten to the power of (log 3)/14, which gives an exponential growth rate of 8% per day. Five-fold slower than without masks.

But 8% per day is still fast.

Even though we might be able to vaccinate large numbers of people by the end of next year, that’s not soon enough. Most of us will have been sick with this – at least once – before then.

I don’t mean to sound like a broken record, but the biggest benefit of wearing masks isn’t that we slow the rate of spread for everyone — exponential growth of 8% is still fast — but that we’re better able to protect the people who need to be protected. Covid-19 is deadly, and we really don’t want high-risk people to be infected with it.

I’ve tried to walk you through the reasoning here — the actual science behind mask policies — but also, in case it wasn’t absolutely clear: please comply with your local mask policy.

You should wear a mask around people who aren’t in your (small) network of close contacts.

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I’m writing this essay the day after New York City announced the end of in-person classes for school children.

This policy is terrible.

A major problem with our response to Covid-19 is that there’s a time lag between our actions and the consequences. Human brains are bad at understanding laggy data. It’s not our fault. Our ancestors lived in a world where they’d throw a spear at an antelope, see the antelope die, and then eat it. Immediate cause and effect makes intuitive sense.

Delayed cause and effect is tricky.

If somebody hosts a party, there might be an increase in the number of people who get sick in the community over the next three weeks. Which causes an increase in the number of hospitalizations about two weeks after that. Which causes people to die about three weeks after that.

There’s a two-month gap between the party and the death. The connection is difficult for our brains to grasp.

As a direct consequence, we’ve got ass-hats and hypocrites attending parties for, say, their newly appointed Supreme Court justice.

But the problem with school closures is worse. There’s a thirty year gap between the school closure and the death. The connection is even more difficult to spot.

Even if you have relatively limited experience reading scientific research papers, I think you could make your way through this excellent article from Chistakis et al.

The authors link two sets of existing data: the correlation between school closures and low educational achievement, and the correlation between low educational achievement and premature death.

The public debate has pitted “school closures” against “lives saved,” or the education of children against the health of the community. Presenting the tradeoffs in this way obscures the very real health consequences of interrupted education.

These consequences are especially dire for young children.

The authors calculate that elementary school closures in the United States might have (already!) caused 5.5 million years of life lost.

Hsiang et al. found that school closures probably gave us no benefit in terms of reducing the number of Covid-19 cases, because children under 18 aren’t significant vectors for transmission (elementary-aged children even less so), but even if school closures had reduced the number of Covid-19 cases, closing schools would have caused more total years of life to be lost than saved.

The problem – from a political standpoint – is that Covid-19 kills older people, who vote, whereas school closures kill young people, who are intentionally disenfranchised.

And, personally, as someone with far-left political views, it’s sickening for me to see “my” political party adopt policies that are so destructive to children and disadvantaged people.

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So, here’s what the scientific data can tell us so far:

  • We will eventually have effective vaccines for Covid-19. Probably within a year.
  • Covid-19 spreads even with social distancing and masks, but the spread is slower.
  • You have no way of knowing the risk status of people in a stranger’s bubble. (Please, follow your local mask orders!)
  • Schools – especially elementary schools – don’t contribute much to the spread of Covid-19.
  • School closures shorten children’s lives (and that’s not even accounting for their quality of life over the coming decades).
  • An individual case of Covid-19 is about twice as dangerous as a case of seasonal influenza (which is scary!).
  • Underlying immunity (from prior disease and vaccination) to Covid-19 is much lower than for seasonal influenza, so there will be many more cases.
  • Most people’s immunity to Covid-19 probably lasts several months, after which a person can be re-infected and spread the virus again.

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So, those are some data. But data don’t tell us what to do. Only our values can do that.

Personally, I value the lives of children.

I wouldn’t close schools.