On ants and infection.

On ants and infection.

I live in a college town. Last week, students returned.

Yesterday’s paper explains that dire punishment awaits the students who attended a Wednesday night party. In bold letters atop the front page, “IU plans to suspend students over party.

In the decade that I’ve lived here, many parties have led to sexual assaults, racist hate speech, and violence. The offending students were rarely punished. But this party was egregious because “there were about 100 people there.

IU officials “have seen a photothat shows a large group of young people standing close together outside a house at night, many of them not wearing masks.

I’ve seen the images – someone filmed a video while driving by. There they are – a group of young people, standing outside.

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Science magazine recently interviewed biologist Dana Hawley about social distancing in the animal kingdom.

When spiny lobsters are sick, their urine smells different. Healthy lobsters will flee the shared den. Leaving is dangerous, since the lobsters will be exposed to predators until they find a new home, but staying would be dangerous, too – they might get sick. To survive, lobsters have to balance all the risks they face.

My favorite example of social distancing in the animal kingdom wasn’t discussed. When an ant is infected with the cordyceps fungus, it becomes a sleeper agent. Jennifer Lu writes in National Geographic that “as in zombie lore, there’s an incubation period where infected ants appear perfectly normal and go about their business undetected by the rest of the colony.

Then the fungus spreads through the ants body, secreting mind control chemicals. Eventually, the fungus will command the infected ant to climb to a high place. A fruiting body bursts from the ant’s head and rains spores over the colony.

Infection is almost always lethal.

If an ant notices that a colony member has been infected, the healthy ant will carry the infected ant away from the colony and hurl it from a cliff.

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The FDA will approve any Covid-19 vaccine that cuts risk by half. It’s very unlikely that a Covid-19 vaccine will cut the risk by more than about two-thirds, and the vaccine will work least well for people who need protection most.

Most likely, the Covid-19 epidemic will end before there’s vaccine. The herd immunity threshold seems to be much lower than some researchers feared – our current data suggest that the epidemic will end after about 40% of the population has immunity.

The herd immunity threshold isn’t an inherent property of a virus – it depends upon our environment and behaviors. In prisons, we’ve seen Covid-19 spread until nearly 90% of people were infected. In parts of New York City where many essential workers live in crowded housing, Covid-19 spread until 50% of people were infected.

In a culture where everyone kissed a sacred statue in the center of town each morning, the herd immunity threshold would be higher. If people wear masks while interacting with strangers, the herd immunity threshold will be lower.

In a world that maintains a reservoir of the virus, though, someone who hasn’t yet been exposed will always be at risk.

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The New York Times recently discussed some of the challenges that colleges face when trying to reopen during the epidemic.

Most schools ban socializing outside “social pods” – the small groups of students that some colleges are assigning students to, usually based on their dorms.

Most administrators seem to believe that a rule banning sex is unrealistic, and are quietly hoping that students will use common sense and refrain from, say, having it with people outside their pod.

In 2012, The Huffington Post published a list of the “Top 10 sex tips for college freshmen.” Their fourth piece of advice (#1 and #2 were condoms, #3 was not having sex while drunk) is to avoid having sex with people who live too close to you. “Students in other dorms = fair game. Students in same dorm = proceed with caution.

I had a big group of friends for my first two years of college. After a breakup, I lost most of those friends.

This is crummy, but it would be much worse if I’d lost my friendships with the only people whom the administrators allowed me to spend time with.

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We can slow the spread of Covid-19, but slowing the spread won’t prevent deaths, not unless we can stave off infection until there is a highly effective vaccine. That might take years. We might never have a highly effective vaccine – our influenza vaccines range in efficacy from about 20% to 80%, and we have much more experience making these.

Our only way to reduce the eventual number of deaths is to shift the demographics of exposure. If we reach the herd immunity threshold without many vulnerable people being exposed, we’ll save lives.

A college would best protect vulnerable students and faculty by allowing the students who are going to socialize to host dense parties for a few weeks before mingling with others. This would allow the virus to spread and be cleared before there was a risk of transferring infections to vulnerable people.

I’d draft a waiver. Are you planning to socialize this semester? If so, come do it now! By doing so, you will increase your risk of contracting Covid-19. This is a serious disease – it’s possible for young, healthy people to die from it. But, look, if you’re gonna socialize eventually, please just get it over with so that you don’t endanger other people.

With this plan, some young people might die of Covid-19. But some young people will die of Covid-19 even if everyone practices social distancing – slowing the spread of infections doesn’t save lives, it delays deaths. And fewer young people would die of Covid-19 than die of influenza each year.

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When confronting cordyceps, which is almost always fatal, ants throw sick colony members off cliffs.

When ants confront less lethal fungal infections, they protect the colony by shifting the demographics of exposure and by ramping up to the herd immunity threshold as quickly as possible.

Malagocka et al. discuss demographics in their review article, “Social immunity behavior among ants infected by specialist and generalist fungi.”

Outside-nest foragers, who have the highest risks of acquiring pathogens from the environment, have limited access to the brood area with the most valuable groups, and are recruited from older individuals, who are less valuable from the colony survival perspective.

Konrad et al. discuss intentional exposure in their research article, “Social transfer of pathogenic fungus promotes active immunization in ant colonies.”

When worker ants encounter an infected colony member, they intentionally inoculate themselves. “Social immunization leads to faster elimination of the disease and lower death rates.

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It feels disquieting for me to defend the behavior of frat guys. Personally, I’d like to see the whole fraternity system abolished. And in March, when we knew less about Covid-19, I was appalled that people went out partying over spring break. But I was wrong. Perhaps inadvertently, those young people were behaving in the way that would save most lives.

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Erika Meitner’s 2006 poem “Pediatric Eschatology” begins

the nurse called back and told us to use bleach
on anything we touch, she said wash everything
in hot water
, insisted we won’t treat you if
you’re asymptomatic, we won’t
, and made us
an appointment anyway. so we waited and waited
with the dog-eared magazines and recall posters

It’s horrible to face the end. It’s almost worse to know that the things you fear are harmless to others. All the asymptomatic cases are like a slap in the face to those whose friends and family have died.

Braun et al. recently published a study in Nature showing that a large number of people who’ve never encountered Covid-19 may already have significant immunity. Parts of the Covid-19 virus are similar to the viruses that cause common colds, and exposure to those viruses might provide the immunity that lets people recover without ever feeling sick.

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I believe we should be doing more to protect young people. Gun control, ending farm subsidies, fighting climate change. Enacting privacy laws to reign in the surveillance capitalists. Breaking up monopolies. Providing good careers despite automation. Making sure that everyone has clean air to breathe and clean water to drink. Getting nutritious food into our nation’s many food deserts. Providing equitable access to health care.

But, punishing young people for socializing?

We’re not making them safer. And we’re not making ourselves safer, either.

Seriously, I know we humans are selfish, but we have to be able to handle an epidemic better than ants.

Red ant: photograph by William Cho

On moral outrage.

On moral outrage.

My family had spring break travel plans for before the shutdown.

We canceled them.

At the time, we feared for our safety. My spouse said to me, “You caught the flu twice this year, even after you were vaccinated, and the second time was the sickest I’ve ever seen you. I’m really worried about what will happen if you catch this new thing, too.”

She wanted me to cancel my poetry classes in the local jail. My father, an infectious diseases doctor and professor of immunology, recommended that I still go in to teach. “If somebody’s in there coughing up a lung, you should recommend he skip class next week,” my father told me.

But I was spooked. I felt glad when the jail put out a press release saying they’d no longer allow volunteers to come in – I didn’t want to choose between helping the incarcerated men and protecting my family.

My spouse is a high school science teacher. She felt glad that her biology classroom has over a dozen sinks. During the final week of school, she asked all her students to wash their hands for 20 seconds as soon as they walked into the room.

My spouse and I are both scientists, but it wasn’t until a week into the shutdown that I began to read research papers about Covid-19. Until then, we had gotten all our information from the newspaper. And the news was terrifying. Huge numbers of people were dying in Italy. Our imbecilic president claimed that Covid-19 was no big deal, making me speculate that this disease was even more dangerous than I’d thought.

Later, I finally went through the data from Italy and from the Diamond Princess cruise ship. These data – alongside the assumption that viral exposure should be roughly similar across age groups, if not higher for school children and young people who are out and about in the world – showed my family that our personal risk was probably quite low.

Still, we stayed inside. We were worried about harming others.

When I saw photographs of beaches packed with revelers, I felt furious. Did those selfish young people not realize that their choices could cause more people to die?

So it was shocking for me to learn that those selfish young people were actually doing the thing that would save most lives.

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We now know that Covid-19 can be transmitted by people who feel no symptoms, and that it was widespread in this country by March.

If we, as a people, had acted earlier, we could have prevented all these deaths. In January, it would have been enough to impose a brief quarantine after all international travel. In February, it would have been enough to use our current strategy of business closures, PCR testing, and contact tracing. In March, we were too late. The best we could do then – the best we can do now – was to slow the spread of infections.

Unfortunately, slowing the spread of infections will cause more people to die.

There’s an obvious short-term benefit to slowing the spread of infections – if too many people became critically ill at the same time, our hospitals would be overwhelmed, and we’d be unable to offer treatment to everyone who wanted it. We’d run out of ventilators.

This problem is exacerbated by the fact that we, as a people, are terrible about talking about death. There’s no consensus about what constitutes a good life – what more would have to happen for you to feel ready to die?

Personally, I don’t want to die. As my mind stopped, I’d feel regret that I wouldn’t get to see my children become self-sufficient adults. But I’d like to think that I could feel proud that I’ve done so much to set them on the right path. Since my twenties, I’ve put forth a constant effort to live ethically, and I’d like to imagine that my work – my writing, teaching, and research – has improved other people’s lives.

I’ve also gotten to see and do a lot of wonderful things. I’ve been privileged to visit four countries. I visited St. Louis’s City Museum when one of my kids was old enough to gleefully play. I have a bundle of some two dozen love letters that several wonderful people sent me.

I’ve had a good life. I’d like for it to continue, but I’ve already had a good life.

Many medical doctors, who have seen how awful it can be for patients when everything is done to try to save a life, have “do not resuscitate” orders. My spouse and I keep our living wills in an accessible space in our home. But a majority of laypeople want dramatic, painful measures to be taken in the attempt to save their lives.

People are making this choice even during the pandemic, when the choice to experience an excruciating death puts medical professionals at risk and reduces the quality of care available for everyone else.

Still. Even without our reluctance to discuss death, there would be a short-term benefit to slowing the spread of infections. The American healthcare system is terrible, and was already strained to the breaking point. We weren’t – and aren’t – ready to handle a huge influx of sick patients.

But the short-term benefit of slowing the spread of Covid-19 comes at a major cost.

The shutdown itself hurts people. The deaths caused by increased joblessness, food insecurity, educational disruption, domestic violence, and loneliness (“loneliness and social isolation can be as damaging to health as smoking 15 cigarettes a day”) are more difficult to measure than the deaths caused by Covid-19. We won’t have a PCR test to diagnose which people were killed by the shutdown.

Those deaths won’t all come at once. But those deaths are no less real, and no less tragic, than the immediate horror of a person drowning from viral-induced fluid buildup in their lungs.

And, perhaps more damning, if the shutdown ends before there’s a vaccine, the shutdown will cause more people to die of Covid-19.

Without a vaccine, slowing the spread of Covid-19 has a short-term benefit of reducing the rate of hospital admissions, at the long-term cost of increasing the total number of Covid-19 cases.

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All immunity fades – sometimes after decades, sometimes after months. Doesn’t matter whether you have immunity from recovery or from vaccination – eventually, your immunity will disappear. And, for a new disease, we have no way of predicting when. Nobody knows why some antigens, like the tetanus vaccine, trigger such long-lasting immunity, while other antigens, such as the flu vaccine or the influenza virus itself, trigger such brief protection.

We don’t know how long immunity to Covid-19 will last. For some coronaviruses, immunity fades within a year. For others, like SARS, immunity lasts longer.

The World Health Organization has warned, repeatedly, that immunity to Covid-19 might be brief. But the WHO seems unaware of the implications of this warning.

The shorter the duration of a person’s immunity, the more dangerous the shutdown. If our shutdown causes the Covid-19 epidemic to last longer than the duration of individual immunity, there will be more total infections – and thus more deaths – before we reach herd immunity.

This is, after all, exactly how a one-time “novel zoogenic disease” like influenza became a permanent parasite on our species, killing tens of thousands of people in the United States each year. Long ago, transmission was slowed to the point that the virus could circulate indefinitely. Influenza has been with us ever since.

That’s the glaring flaw in the recent Harvard Science paper recommending social distancing until 2022 – in their key figure, they do not incorporate a loss of immunity. Depending on the interplay between the rate of spread and the duration of immunity, their recommendation can cause this epidemic to never end.

And, if the shutdown ends before we have a vaccine, the lost immunity represents an increased death toll to Covid-19. Even neglecting all the other harms, we’ll have killed more people than if we’d done nothing.

This sounds terrifying. And it is. But the small glimmer of good news is that people’s second infections will probably be less severe. If you survive Covid-19 the first time you contract it, you have a good chance of surviving subsequent infections. But prolonging the epidemic will still cause more deaths, because herd immunity works by disrupting transmission. Even though an individual is less likely to die during a second infection, that person can still spread the virus. Indeed, people are more likely to spread the virus during subsequent infections, because they’re more likely to feel healthy while shedding infectious particles.

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This calculation would be very different if people could be vaccinated.

Obviously, vaccination would be the best way to end this epidemic. In order to reach herd immunity by a sufficient number of people recovering, there would have to be a huge percentage of our population infected. Nobody knows how many infections it would take, but many researchers guess a number around 60% to 70% of our population.

Even if Covid-19 were no more dangerous than seasonal influenza (and our data so far suggest that it’s actually about four-fold more dangerous than most years’ seasonal influenza), that would mean 200,000 deaths. A horrifying number.

But there’s no vaccine. Lots of people are working on making a vaccine. We have Covid-19 vaccines that work well in monkeys. But that doesn’t necessarily mean anything in terms of human protection. We’ve made many HIV vaccines that work well in monkeys – some of these increase the chance that humans will contract HIV.

It should be easier to make a vaccine against this coronavirus than against HIV. When making a vaccine, you want your target to mutate as little as possible. You want it to maintain a set structure, because antibodies need to recognize the shape of external features of the virus in order to protect you. HIV mutates so fast that its shape changes, like a villain constantly donning a new disguise. But the virus that causes Covid-19 includes a proofreading enzyme, so it’ll switch disguises less.

Still, “easier to make a vaccine against than HIV” is not the most encouraging news. Certain pharmaceutical companies have issued optimistic press briefings suggesting that they’ll be able to develop a vaccine in 18 months, but we should feel dubious. These press briefings are probably intended to bolster the companies’ stock prices, not give the general public an accurate understanding of vaccine development.

Realistically, a Covid-19 vaccine is probably at least four years away. And it’s possible – unlikely, but possible – that we’ll never develop a safe, effective vaccine for this.

If we end the shutdown at any time before there is a vaccine, the shutdown will increase the number of people who die of Covid-19. The longer the shutdown, the higher the toll. And a vaccine is probably years away.

The combination of those two ideas should give you pause.

If we’re going to end the shutdown before we have a vaccine, we should end it now.

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To be absolutely clear, vaccination would be the best way to resolve this crisis. Vaccination saves lives. The basic principle of inoculation was used for hundreds of years in Africa, India, and China, before it was adapted by Edward Jenner to create the first smallpox vaccine.

For a vaccine to end the Covid-19 epidemic, enough people will need to choose to be vaccinated for us to reach herd immunity.

Unfortunately, many people in the United States distrust the well-established efficacy and safety of vaccines. It’s worth comparing Covid-19 to seasonal influenza. On a population level, Covid-19 seems to be about four-fold more dangerous than seasonal influenza. But this average risk obscures some important data – the risk of Covid-19 is distributed less evenly than the risk of influenza.

With influenza, healthy young people have a smaller risk of death than elderly people or people with pre-existing medical conditions. But some healthy young people die from seasonal influenza. In the United States, several thousand people between the ages of 18 and 45 die of influenza every year.

And yet, many people choose not to be vaccinated against influenza. The population-wide vaccination rate in the United States is only 40%, too low to provide herd immunity.

Compared to influenza, Covid-19 seems to have less risk for healthy young people. Yes, healthy young people die of Covid-19. With influenza, about 10% of deaths are people between the ages of 18 and 45. With Covid-19, about 2% of deaths are people in this age group.

I’m not arguing that Covid-19 isn’t dangerous. When I compare Covid-19 to seasonal influenza, I’m simply comparing two diseases that are both deadly.

I get vaccinated against influenza every year.

Yes, you might have heard news reports about the influenza vaccine having low efficacy, but that’s simply measuring how likely you are to get sick after being vaccinated. We also know that the vaccine makes your illness less severe.

The influenza vaccine saves lives. The data are indisputable.

But people don’t choose to get it! That’s why I think it’s unfortunately very likely that people whose personal risk from Covid-19 is lower than their risk from influenza will forgo vaccination. Even if we had access to 300 million doses of a safe, effective vaccine today, I doubt that enough people would get vaccinated to reach herd immunity.

Obviously, I’d love to be wrong about this. Vaccination saves lives.

Please, dear reader, get a flu vaccine each year. And, if we develop a safe, effective Covid-19 vaccine, you should get that too.

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We don’t have a vaccine. The shutdown is causing harm – the shutdown is even increasing the total number of people who will eventually die of Covid-19.

Is there anything we can do?

Luckily, yes. We do have another way to save lives. We can change the demographics of exposure.

Our understanding of Covid-19 still has major gaps. We need to do more research into the role of interleukin 6 in our bodies’ response to this disease – a lot of the healthy young people who’ve become critically ill with Covid-19 experienced excessive inflammation that further damaged their lungs.

But we already know that advanced age, smoking status, obesity and Type 2 diabetes are major risk factors for complications from Covid-19. Based on the data we have so far, it seems like a low-risk person might have somewhere between a hundredth or a thousandth the chance of becoming critically ill with Covid-19 as compared to an at-risk person. With influenza, a low-risk person might have between a tenth and a hundredth the chance of becoming critically ill.

The risk of Covid-19 is more concentrated on a small segment of the population than the risk of influenza.

To save lives, and to keep our hospitals from being overwhelmed, we want to do everything possible to avoid exposing at-risk people to this virus.

But when healthy young people take extraordinary measures to avoid getting sick with Covid-19 – like the shutdown, social distancing, and wearing masks – they increase the relative burden of disease that falls on at-risk people. We should be prioritizing the protection of at-risk people, and we aren’t.

Because this epidemic will not end until we reach the population-wide threshold for herd immunity, someone has to get sick. We’d rather it be someone who is likely to recover.

Tragically, we already have data suggesting that a partial shutdown can transfer the burden of infection from one group to another. In the United States, our shutdown was partial from the beginning. People with white-collar jobs switched to working remotely, but cashiers, bus drivers, janitors, people in food prep, and nurses have kept working. In part because Black and brown people are over-represented in these forms of employment, they’ve been over-represented among Covid-19 deaths.

There is absolutely no reason to think that poor people would be more likely to safely recover from Covid-19 – indeed, due to air pollution, stress, sleep deprivation, limited access to good nutrition, and limited access to health care, we should suspect that poor people will be less likely to recover – but, during the shutdown, we’ve shifted the burden of disease onto their shoulders.

This is horrible. Both unethical and ineffective. And, really, an unsurprising outcome, given the way our country often operates.

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If we want to save lives, we need for healthy younger people to use their immune systems to protect us. The data we have so far indicates that the shutdown should end now — for them.

It will feel unfair if healthy younger people get to return to work and to their regular lives before others.

And the logistics won’t be easy. We’ll still need to make accommodations for people to work from home. Stores will have to maintain morning hours for at-risk shoppers, and be thoroughly cleaned each night.

If school buildings were open, some teachers couldn’t be there – they might need substitutes for months – and neither could some students, who might switch to e-learning to protect at-risk family.

We’ll need to provide enough monetary and other resources that at-risk people can endure a few more months of self-isolation. Which is horrible. We all know, now that we’ve all been doing this for a while, that what we’re asking at-risk people to endure is horrible. But the payoff is that we’ll be saving lives.

Indeed, the people who self-isolate will have lowest risk. We’ll be saving their lives.

And no one should feel forced, for financial reasons or otherwise, to take on more risk than they feel comfortable with. That’s why accommodations will be so important. I personally would feel shabby if I took extreme measures to protect myself, knowing that my risk is so much lower than other people’s, but you can’t look at someone in a mask and know their medical history, much less whom they might be protecting at home.

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All told, this plan isn’t good. I’m not trying to convince you that this is good. I’m just saying that, because we bungled things in January, this is the best we have.

If we could go back in time, we’d obviously do things differently. It’s only based on where we are now that physicians like David Katz argue we need to end the shutdown based on the principle of “harm minimization.”

Based on the data we have, I agree.

Ending the shutdown now, but only for some, will save lives.

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So, those selfish young people crowding on beaches? I looked at the photos and hated them.

But it turns out that their selfish actions were actually the exact plan that will save most lives.

I’ve had to swallow my moral indignation. I hope you can too.