| 1. They have the virus go from like 5% infected to 70% in two weeks in that scenario. Given what we know about the incubation period and they assume about the infectious period, more than half the population has to be infected (and probably even infectious) somewhere along that curve. 2. Their model predicts that the peak of the epidemic in Italy should have been before March 5th (first death on February 22nd + 14 days, at which point easily more than half the population is infected). There should have been a sharp drop in new cases about a week later, as the virus burnt itself down. But here we are three weeks later, and it's still not entirely clear that the peak has been found. Italy did not institute significant nation-wide measures until March 9th, so the "slowdown from measures" explanation makes no sense. 3. Agreed. But their entire model is predicated on treating the entire country as a single unit. That's probably a part of the reason why the results are so absurd. I don't think it's fair to excuse the model for regional differences, but require any criticism of the model to take them into account. 4. The difference between the model's prediction and apparent reality is likely to be about a factor of 200. Even assuming everybody on the ship was actually infected, that only cuts it to a factor of 40 difference. And it's really not just that single case. Consider that infamous Washington state nursing home. 120 residents, 35 dead from Covid to date. Even if we assume that every single one of the 120 was infected despite not testing positive, that still an IFR of 30%. Sure, it's a high-risk segment. But it's also a large enough segment a 30% IFT for them makes it quite impossible for the population-wide IFR to be 0.01%. (Re: your last point, they had two parameters. One for being at risk of becoming a serious case, and another of dying if serious. The two need to be multiplied to get their predicted IFR. They assumed that 0.1% of population were at risk to become severe cases, and 15% of the severe cases died. So about 0.01%). |
On the other, I don't understand how after making so many (often reasonable) assumptions in your arguments, you can say that it's "quite impossible" for the total infected to be so high, or the population-wide IFR to be three orders of magnitude lower than a nursing home or any other special case that you do not fully understand.
Here are some of those assumptions, which again do not all seem unreasonable to me:
- A mild case would likely be detectable by a PCR test for 8+ days
- The PCR test does not have a high false-negative rate in mild cases (see https://www.researchsquare.com/article/rs-17319/v1)
- Italy has not already had a sharp drop in new infections/most new infections are being identified as cases within two weeks
- Italy did nothing to slow the rate of infection until the full lockdown was in effect (but slower spread would mean higher mortality, no matter the reason)
- COVID-19 was the only/main thing that contributed to mortality in the special cases