Consider Controlled Infection

In many places long ago, in families with many kids, as soon as one kid caught an illness, parents would put the other kids in close contact, so they could all catch it at once. Because it was less trouble to care for all the kids in a family at once than to care for them one at a time.

Should we also consider controlled infection to deal with our current pandemic? Like controlled burns that prevent later larger fires, it might be a good idea to expose some people early on purpose.

Today a coronavirus is spreading rapidly across China, and the world, and many are trying hard to resist that spread. One obvious reason to resist is the hope that the spread can be completely stopped, limiting how many are exposed. However, once a contagious enough virus has spread to enough people and places, this scenario becomes quite unlikely; the virus will soon spread to most everywhere that isn’t high isolated.

Unfortunately, we are probably already past this point of no return with coronavirus. It seems to spread easily, apparently including via people who are contagious but don’t show symptoms. It already seems to have spread from its initial region to infect many people in a great many other Chinese cities and regions (thousands infected, dozens dead). And that’s with keeping everyone home from work, which can’t last much longer. Once this virus comes to infect most of China, it seems hard to imagine a strong enough China wall (a 24-day quarantine for everyone leaving) to keep it from spreading further. Especially since China & WHO are arguing against such a wall, and we already have confirmed a few hundred cases outside China; they’ve doubled every week for four weeks.

Another reason to resist virus spread is in the hope that a vaccine (or other effective treatment) will be available before it spreads everywhere, stopping the spread at that point. There’s some hope for a drug soon to prevent infections, but the odds are poor and if that doesn’t work prospects are dim. Alas “typically, making a new vaccine takes a decade or longer”, and estimates for this case are at least 18 months. That doesn’t include time to manufacture and distribute it, once we know how to make it.

As of yesterday, total known deaths were 1384, a number that’s had a 6 day doubling time lately. (A very different method estimates 7 day doubling.) At that rate, in four months deaths go up by a factor of a million, which is basically the whole planet. So unless long-term growth rates slow by more than a factor of four, there’s probably not time for a vaccine to save us.

If the virus spreads to most of the world, so most everyone is exposed, then the fraction of the world that dies depends how deadly is the virus, which we just don’t know, and can’t control. Maybe we’ll get lucky, and this one isn’t much worse than influenza. But we are probably not so lucky. The fraction of the world that dies also depends our systems of social support, which we can do more to influence.

I’m not a medical professional, so I can’t speak much to medical issues. But I am an economist, so I can speak to social support issues. I see two big potential problems. One is that our medical systems have limited capacities, especially for intensive care. So if everyone gets sick in the same week or two, not only won’t the vast majority get much of help from hospitals, they may not even be able to get much help from each other, such as via cleaning and feeding. Perhaps greatly increasing death rates. This problem might be cut if we spread out the infection out over time, so that different people were sick at different times.

The other related problem is where many non-sick people stay away from work to avoid getting sick. If enough people do this, especially at critical infrastructure jobs, then the whole economy may collapse. And not only is a collapsed economy bad for most everyone, sick people do much worse there. Not only can’t they get to a doctor or hospital, they might not even be able to get food or heating/cooling. Infected surfaces don’t get cleaned, and maybe even dead bodies don’t get removed. Thieves don’t get stopped. And so on. We can already see social support partially collapsing in Wuhan now, and it’s not pretty.

There’s an obvious, if disturbing, solution here: controlled exposure. We could not only insist that critical workers go to work, but we might also choose on purpose who gets exposed when. We can’t slow down infection very much, but we can speed it up a lot, via deliberately exposing particular people at particular times, according to a plan.

Such a plan shouldn’t just expose random people early, as they’d be likely to infect others around them. Instead, groups might be taken together to isolated places to be exposed, or maybe whole city blocks could be isolated and then exposed at once. Exposed groups should be kept strongly isolated from others until they are not longer very infectious.

Those who work in critical infrastructure, especially medicine, are ideal candidates to go early. Such a plan should only expose a small fraction of each critical workforce at any one time, so that most of them remain available to keep the lights on. If critical workers could be moved around fast enough, perhaps different cities could be exposed at different times, with critical workers moving to each new city to be ready to keep services working there.

Such plans can help even if some people who are infected and recover can get reinfected later. As long as being infected gives enough people enough immunity for a long enough time period, that is enough for this plan to spread out the infections over a time period of similar duration, so medical service needs don’t all appear together. Even an immunity of only two months, which is extremely short compared to most diseases, would allow a lot of spreading.

People selected to be exposed earlier might be paid extra cash, to compensate for perceived extra risk. (Maybe X days worth of their usual wages, so as not to especially select the poor.) Or perhaps they could be paid in extra priority for sick associates if medical help is rationed later. (I’d seriously consider both kinds of offers.) We might even be able to implement a whole plan like this entirely via volunteers, though adding that constraint may make a strong plan harder to design. A compromise might be to let city blocks vote on if to be paid to go early together. I’m willing to help in design work on this, if that could help make the difference.

I don’t have a detailed plans to offer, and obviously any such plans should be considered very carefully. Also obviously, such plans might face strong opposition, which could undermine them. If they were designed or implemented badly, they might even make things worse. But the alternative is to risk having large fractions of the population get sick at once, while the economy collapses due to critical workers staying home to avoid getting sick. A scenario which could end up a lot worse.

So authorities, and the rest of us, should at least consider controlled infection as a future option. I’m not saying we should start such a plan now; maybe that drug will work, and it will all be over soon. But if not, we should start to ask when we might learn what could help us decide, what might be a good time to pull the trigger on such a plan, and how to prepare earlier for the possibility of wanting to pull such a trigger later.

Added 17Feb: See also my next post elaborating the intuition behind why and when deliberate exposure could make sense.

Added 03Mar: See also my spreadsheet model, and further discussion.

Added 15Mar: See also elaborations of spreadsheet model.