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Comment by barbegal | Hacker News Reader

The doubling period of Covid-19 is between 1.8 and 4.1 days where large scale quarantine measures aren't being taken [1][2]. The conference is in 43 days so without large scale quarantines and stopping large events then the number of cases in the US could grow to as many as 800,000 assuming a doubling period of 3 days. It seems therefore fairly obvious that most large events in April will have to be cancelled.

[1] https://link.springer.com/article/10.1007%2Fs15010-020-01401... [2] https://onlinelibrary.wiley.com/doi/abs/10.1002/jmv.25723

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Thanks for sharing the journal articles.

According to [1], on January 31, 2020 US had 6 cases of Covid-19. And according to several news sites, as of March 2, 2020, there are 101 cases.

If I did the math correctly, that seems to be doubling about every four days or so, which lines up with the doubling period mentioned.

Its difficult to tell because the US hasn't been doing as much testing as other countries. You can look at the curves for various countries at https://covid.bio/ Most countries that haven't initiated large scale quarantines have a doubling period of between 1.5 and 5 days

On the other hand, one wonders if that curve measures not infection rates, but testing kit manufacturing output.

I think the numbers can't be looked at that way for a variety of reasons, primarily the fact that we are rapidly expanding testing capability in the US right now, so we will see a rapid increase in the number of diagnosed cases. However that does not mean there is the same rapid increase in the number of cases so quickly. Basically we are going to be catching up with cases from the past 2-4 weeks in the coming week.

the us has tested less than 500 cases in total

doubling about every four days or so, 6 + 31 days would be about 800 cases.

If we have about 100 cases today, and that doubles every 4 days, we'd have about 60k cases in 37 days.

    (6 + 31) / 4 = 9.25
    2 ^ 9.25 = 608
    608 * 100 ~= 60k

When I wrote "6 + 31 days" I meant "6 (initial) cases, 31 days later". I thought that was clear in context.

Ah, yes `6 * 2 ^ (31 / 4)` is much larger than 100. Good point.

Your March 2 numbers include Diamond Princess cases (45?) which have not been in contact with the rest of the population.

No there are other estimates of a few hundred cases in the bay area that are sensible. Or at least they were a week ago. To get two in-the-wild cases serious enough for hospitalization and testing (overriding the CDC testing criteria at the time) you'd expect there to be at least around 100-200 cases at the time of hospitalization.

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