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Comment by sarnowski | Hacker News Reader

My vague understanding is, that the tests can also test positive for antibodies from other similar viruses. They have a significant false-positive rate that you should not rely on a positive („you are immune“) result but overall they will provide a big picture approximation how many citizens might have already resistance. They are not good enough for a rumored „immune certification“.

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Currently we have no idea how many people have had covid. We have a good idea how many have died, but no country has managed to do the kind of testing that would give a good indication of how many people have been infected. Do 2% of people getting it die, or 0.2%, or 0.02%? Testing 1 million people at random across the country will give good results of not only how deadly it is, but also how likely it is to spread in different areas of the country.

We have a pretty good idea it isn't 0.02% because there's an upper bound on the infection rate (around 75%) and the number of bodies is known and in all cases exceeds 0.3% of the maximum possible infections.

How did you come up with 0.3% number of bodies / maximum possible infections, aka total population? I'm trying to wrap my head around this whole mess...

Take Lombardy, hardest hit region in Europe. 1130 deaths / million, or about 0.1% death rate. All German states are under 100 deaths per million, which is less than 0.01% death rate. Sanity check: Bayern, 1.2k deaths/13M people ~ 0.01%.

Of course, this is a lower bound estimate assuming all people in a given region have got through the disease. Which is definitely not true. To figure out how bad is going to get we need the total number of infected people. Hopefully the random testing strategy will shed some light on that number. But at least we start [much] lower than 0.3%.

https://covid19.quersive.com/chart?c=M&e=IT-Lombardy&e=DE-BW...

In NYC, 0.16% of the population's died from it, so that's a hard lower bound.

Thanks!

> They are not good enough for a rumored „immune certification“.

And how about being tested negative, and a few weeks later being tested positive? I suppose that would improve the accuracy.

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