April 10, 2020    America

Maximizing Infection without Overshooting ICU Capacity

There is a good reason to believe that New York City, in the end, will come out better off than other cities. Here is why:

The Japanese government has been using the term “overshoot” in English to describe the situation where the number of critically ill patients exceeds the number of available ICUs. English speakers have been puzzled as to why they chose that word because “overshoot” would imply that there is a desirable target beyond which is an “overshoot.” The word makes no sense because there is no such thing as a desirable target. But in thinking about how Singapore, Hong Kong, and Taiwan are now struggling with the second wave of the spread triggered by their own citizens coming home from the US and Europe, I realized that there is indeed a desirable target, although this is not what the Japanese government intended.

If we are to lock down a city, we actually want to maximize the ICU capacity without overshooting it. Let’s say some city orders a lockdown very early and succeeds in flattening the curve so well that they only used 5% of their ICU capacity. This may sound like a good thing, but it would mean that only a tiny percentage of the population would develop immunity from the lockdown.

Singapore, Hong Kong, and Taiwan are about to lose control of the spread from the second wave because most of their citizens are not immune from C19, thanks to the success of their early containment efforts from the first wave. My hypothetical city above will eventually face the same fate despite the initial “success.”

The governments of Taiwan and Singapore have databases of their citizens with their medical history and travel records, which allow them to proactively identify high-risk individuals before they even show symptoms. The US government has no such database. If Taiwan and Singapore cannot contain the spread, there is no chance any American state can. In fact, no American state or city has managed to pull off such a feat in the first wave. New York quickly gave up contact tracing after the first outbreak in Westchester.

It is inevitable that, if the vast majority of the population do not have immunity, the new waves of infection will continue to threaten every city and state until we have a vaccine, which will be a year from now.

After the current crisis in New York City, if a significant percentage of New Yorkers build immunity against C19, we would be able to restart our economy without worrying about triggering another big surge as every person who is immune would hamper the spread. Even if we have another wave, we wouldn’t “overshoot” the ICU capacity, and we would be able to steadily increase the number of people who are immune.

In other words, ICUs should be functioning at full capacity at all times until we have a vaccine. That is our target. This is bad news for the healthcare workers, but the alternative would be to shut down the whole economy for a year.

The cost of locking down a large city is unimaginably high. If we are going to pay that price, we want the greatest possible number of people to become immune from it. If it’s possible to infect, say, 25% of the population without exceeding the ICU capacity by locking down the city for a month, infecting only, say, 5% would be a huge waste of the month-long lockdown. We can see a lockdown as a type of investment. We would want to infect as many people as possible for the same price.

If what I’m suggesting here is valid, we would not want to lock down a city too early. We want to time it just right so that we can maximize the number of infections without overshooting the ICU capacity.

After this first wave, hopefully, antibody tests would be widely available, so that we can determine what percentage of New Yorkers were infected. From this data, we would be able to prepare for the second wave and maximize the infection rate for the next lockdown without overshooting. We might achieve the “herd immunity” status after that.