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Comment by kgwgk | Hacker News Reader

If the true infection rate is 50% they are very unlucky with their tests because less than 40% of the people tested give a positive.

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Not really. Antibody tests like this one measure the total number of people who've been infected at some point in the relatively recent past, whereas the diagnostic tests New York is using only detect current active infections, so it's easy for the percentage of infections measured by the former to be higher than the latter.

When articles like this compare the number of known cases detected with the PCR diagnostic tests with the higher estimate based on antibody testing, they're comparing the sum of all cases detected since the start of PCR coronavirus testing with a point-in-time estimate of the proportion of the population that currently has antibodies for exactly this reason.

That’s true. We could have 25% active infections and 25% not currently infected but who were infected in the past. I still think the actual numbers may be be lower (but higher than the reported figures, of course).

> less than 40% of the people tested give a positive.

FWIW, Queens and Brooklyn (Kings county) are at 50.7% and 48.3% positive tests respectively.

https://covid19tracker.health.ny.gov/views/NYS-COVID19-Track...

I meant people being tested nowadays, not cumulative numbers.

Today: Kings 548/1835 = 29.9% and Queens 786/2428 = 32.4%

If we're going to talk about the total number of people who have been infected, wouldn't it make more sense to use the overall test rate?

My point was that the number of people currenlty infected is surely lower than 30%, given that only 2% of the population is already confirmed and testing a suspected case today will return a negative 70% of the time.

But as another commenter said, it's not impossible that there are many other people who had infection which is not currently active.

Using the overall test rate doesn't really help, I think.

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