Basic Coronavirus Predictions

Attempting to predict things is hard, especially about the future. Right now I am doing some very rough estimates of where I expect things to be in two weeks. (on 3/22/2020)

South Korea:
The outbreak in Korea seems to be slowing down. A basic “logistic curve”, has a second derivative of 0 at the half-way point. We see some fluctuations of the first derivative from 3/3 to 3/6, so we see the halfway point is between 5.3 and 6.7. Averaging, we get ~6000, so the outbreak is going to stabilize at ~12000 total infections eventually and given the slow rate of growth I might take a while to get there.
Estimate: 10000 in 2 weeks

Iran:
Iran’s numbers are assumed to be fake, however, the questions here is not what the real numbers are, but what the fake numbers are going to be. It’s possible that a large % of major cities to be infected, but that doesn’t mean those will be tested or reported.

Now, the somewhat surprising conclusion is that Iran also has a decreasing day to day count with second derivative being negative between 3/6 and 3/7, with average of 5300 cases. However, due to numbers being fake one doesn’t expect this to follow a logistic curve, unless somebody want to make it follow a logistic curve, while maintaining plausible deniability, which I think they will.

Also, the day to day increase is still double that of Korea and the previous growth rate is higher, thus I don’t feel as good trying to use that methodology here, but I will put a tentative estimate of: 10600

Iran also has a completed case fatality rate D / (D + R) is 194 / (194 + 2,134) = 8.3%. Looking at Chinese data (also fake), we see a similar D / (D + R) at 57400 or so, which is 71% of their approximate eventual stabilization point, which gives us an even lower estimate of 9.2K for eventual stabilization for Iran. I know that a number of sources have said the society is collapsing over there, but this doesn’t seem to be reflected in the slow-down or the high numbers of recovered, so I am going to stick with 10600 estimate.

Estimate: 11000 (rounding up due to severity) – I suspect it’s most likely to be an under-estimate.

Italy

Italy is number 2 of the number of infections that it does not seem that there is any sort of slow down in the first derivative. They have been growing 20-25% every day for a week consistently.

Assuming 23% growth a day for two weeks, we get 18.1 times the cases = 133793. This is likely an overestimate. China grew from 7711 cases to 66492 cases in two weeks. Once again, those numbers are fake, but the estimate seems more correct. They had a similarly high 30-40% D / (D+R) around 11 thousand.

Estimate: 66000

USA

USA is nowhere near the midway point of the epidemic and the numbers are also fake. D / (D + R) is abysmal at 70% (!!!!), which all mean the epidemic is just getting started. Italy took about two weeks to grow from 150 to 7375. 150 in Italy is a smaller % of population than 554 in the US, so a similar increase is possible, putting the US at ~27000, except for it would be once again constrained by testing. China grew from 1975 to 37198 in two weeks as well at a similar % of population, which is an 18.8 fold increase, which is 10 434 – a more plausible number. US would be less extreme in containing it than china (driving numbers up), but testing less than Italy, driving numbers down, hence I am going with 10k prediction.

Final predictions:

South Korea: 10000
Italy: 66000
Iran: 11000
US: 10000