How Deadly is COVID19? NYC Sets a Lower Bound

A body is picked up from the Wyckoff Heights Medical Center on April 2, 2020 in Brooklyn, New York. (Photo by ANGELA WEISS/AFP via Getty Images)
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There’s been a lot of discussion about how deadly COVID19 is. It’s always seemed highly unlikely that the number of fatalities per lab-confirmed cases is at all representative of the true percentage of people who die from being infected with COVID19. That number was over 3% in China, about 5.4% in the US currently and has ranged as high as 10% in Italy. Far too many cases are escaping lab confirmed detection for those to be close to accurate.

But what’s the lower bound? Many researchers seem to think something in the neighborhood of 1% is most likely. But that’s more a ballpark than any sort of real estimate. It could be substantially lower or higher. Serology tests will eventually get us to something like hard evidence. But we’re not close to there yet.

Meanwhile there have been others arguing for much lower percentages, as far down as .1%. Some of those people are driven by politics or ideological investment, holding out for the idea that the actual mortality is comparable to the flu. But not all of them. Bear in mind that even if COVID19 only killed .2% of its victims the potential cost in lives would be vastly greater than the flu since nobody has any immunity to it at all.

But here’s one number that is worth noting.

As of two days ago New York City reports 13,683 COVID19 deaths. 9,101 of those are lab confirmed and 4,582 are diagnosed on the basis of symptoms but with no lab confirmed test. The City has a population of 8,398,748 million, as of the 2018 Census estimate. So as of now, .16% of New York’s population has died from COVID19.

Even if you held the number to just those with a lab confirmed diagnosis, you’re still at .11%

We don’t know how many New Yorkers have been exposed to COVID19. For the city this is a critical question since it will give us important information about possible 2nd or 3rd waves of the disease, as well as a better understanding of disease mortality. But it is certainly not the case that every New Yorker has been exposed. So this gives us an extremely firm lower bound. Even if you assume that wildly more New Yorkers than anyone thinks was infected you’re still way over .2%. Indeed, if half of New Yorkers have been infected, that gets you to about a .35% rate of fatality per infection.

I don’t think many people were seriously thinking only .1% of people died of COVID19. But unfortunately New York City has now definitively ruled that out possibility.

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