Should contact bans be lifted in Germany? A quantitative prediction of its effects

Jean Roch Donsimoni; René Glawion; Bodo Plachter; Constantin Weiser; Klaus Wälde

We would like to emphasize that this property of our model is crucial for our long-run predictions and the short-run …ndings. The long-run number of individuals that, once the epidemic is over, were ever reported to be sick is the probability to get sick after an infection, r = 10%; times the long-run share of infected individuals, = 60%; times population size, N = 83:1 million, i.e. the long-run number of sick individuals equals 4:99 5 million. This is the number of sick individuals in the "normal"scenario of Donsimoni et al. (2020a,b) . In their "optimistic Hubei scenario", they assume that the population share of ever infected individuals once the epidemic is over amounts to = 6% only. In this scenario, the long-run number of sick individuals is 10% 6% 83:1 million =498:6 thousand individuals, i.e. roughly 0.5 million individuals. Once this quantity is …xed, any public health measure in our model only shifts the number of sick individuals over the duration of the epidemic. RSC reduces the sickness rate 12 from (2) in the short-run but only delays the infection of the rest of N ever 2 (end) from (4). We admit that this is a strong implication of our model but we only "translate" assumptions made in more general not model-based discussions. 9 Given that this is a strong assumption and given our Gompertz curve estimation of the current situation in Germany illustrated in …gure 3, we are now in the lucky situation that we can do without a strong assumption for N ever 2 (end) for the current RSC. For the current regime (but not for the end of the entire COVID19 epidemic), …gure 3 tells us that we are converging in May or June to a value of roughly 184; 000 sick individuals. To make clear that this value is 8 As discussed below, we assume that a lift on 20 April would imply observable e¤ects only around one week later. 9 In ongoing work we study the historical evidence about r from other epidemics and pandemics. No systematic evidence seems to be available at this point. We are grateful to dozens of epidemiologists, virologists, economists and decision-makers for discussions of this point.