The low case fatality of #COVID19 in Europe over the last month still triggers a lot of speculation on what might be different now: not much!

It can be almost entirely explained by
* steep age dependence of fatality
* a markedly different age distribution of cases
1/5

Comparing the age distributions of confirmed cases in Switzerland before and after June 1st, you see a strong shift towards young adults and very few cases in people >70y.
2/5

The drop in crude case fatality ration (CFR) in CH since April is very consistent with the IFR averaged over the age distribution of cases. So the currently low CFR is not particularly mysterious.
3/5

You'd expected confirmed cases to be biased towards severe cases, but with many tests being in travel returnees or in cases identified via contact tracing, this bias is hopefully much less severe than it used to be.
4/5

In previous outbreaks, we have often observed a shift from younger to older groups. For more on this, go read @firefoxx66 https://twitter.com/firefoxx66/status/1296080742607355904