Pandemic Dynamics
A few days ago modeling of the impact of the pandemic on the US population carried out by a group at Imperial College was presented to the White House. According to the New York Times, the gravity implied by these models is what shifted the White House from soft denial to a more focused response. I want to show you two graphs from that New York Times article.
This first graph shows a rapid and macabre severity of an uncontrolled pandemic. It is also interesting to see that the peak is earlier in the UK but also higher, presumably because of a denser population hence a faster and deeper spread until herd immunity is reached. Also important to note that three months is about the duration of the whole disaster. Unfortunately I expect this model to hold in countries that have a difficult time implementing effective social distancing, for example in countries that are poor and with high population density. For these countries, the ordeal could be over before a vaccine becomes relevant. It is easy to see how this graph would focus the minds at the White House. Mitigation is a must!
This second graph shows the impact of various mitigation efforts on the pandemic’s impact. ‘Critical care beds occupied’ is a variable that correlates very closely with fatalities. So that according to this model the peak number of death could only be mitigated at most to a third of what it would be without any mitigation. Total fatalities (proportional to the surface of these peaks) could also not be mitigated to be less than a third of the pandemic without mitigation. There are today two live examples that illustrate that this model’s predictions are wrong.
The first counterexample is China. Here is a curve of the total number of Coronavirus deaths in China. This shows that after a period of about three months (January 22 until now) the number of fatalities has effectively plateaued. The total number of fatalities is only a tiny fraction of what the Imperial College model seems to imply. Quarantine by the Chinese method seems to have stopped the virus. In fact, today China registered no new cases in the Hubei sealed area, or outside of it. The only new cases registered are from new arrivals at the airport, where these new arrivals are forced to quarantine for two weeks (and asked to pay for it). You are probably thinking that the Chinese government can take measures that the US government could not take, that China can not be relied on to be a model for a democracy. But South Korea, a democracy and a developed country shows similar trends, the way social distancing has been implemented has been different from China (no totally sealed area) but seems equally effective.
The second counter example is the Vo’ Euganeo situation. This small town of 3341 people tested everyone, quarantined those who were positive and sealed the town. Two weeks later the virus has been virtually eliminated (perhaps totally eliminated in a few more days). A rich democratic enclave in which effective social distancing stops the number of fatalities at a very low level.
So there is hope. Some measures can stop the pandemic in a rather short period of time and with a minimal number of casualties. What we don’t know yet is how does this exactly end? What happens if China reopens its sealed area? Will a virus dormant in someone cause a resurgence in new cases? Perhaps. But even in that case the problem could be tractable. This second wave of contagion would meet a much more informed population, a government hopefully a lot better prepared to test and isolate a small number of new cases. A second chance to fight the epidemic from the very start.
And how about the US? Well, the epidemic is still in its rather early stage here. We are only about a month in (China is now three months in), the number of deaths is still rising sharply, effective social distancing has been ordered starting about a week ago, so we might see a peak number of deaths in another week or two. Young italians also ignored the lockdown order at first and after a week they shifted to a more cautious behavior. The federal testing fiasco will be remediated quickly, this morning I read about an “at home testing kit” coming soon. All these being considered, I personally think (I should say speculate) that the US pandemic will taper off within two months. We will then be better prepared to deal with a potential second wave of cases.
The bad news is that the only effective way to mitigate the pandemic comes at a very high economic cost. The good news is that the time frame seems rather short. Another good news in my view is that I expect the coming out of this disaster to be explosive, I certainly am feeling antsy here in my home in Sacramento. As soon as the danger is away I shall celebrate (and consume) like it’s 1999.
Stay safe!
Marc Anselme
