We’ve been comparing the UK and Germany to try to explain the comparatively low fatality rates in Germany. The answers are sometimes counterintuitive. For example, it looks as if the low German fatality rate is not due to their superior testing capacity, but rather to the fact that the average German is less likely to get infected and die than the average Brit. Why? There are various possible explanations, but one that looks increasingly likely is that Germany has more immunological “dark matter” – people who are impervious to infection, perhaps because they are geographically isolated or have some kind of natural resistance. This is like dark matter in the universe: we can’t see it, but we know it must be there to account for what we can see. Knowing it exists is useful for our preparations for any second wave, because it suggests that targeted testing of those at high risk of exposure to Covid-19 might be a better approach than non-selective testing of the whole population.
The contents of this article may well be wrong, as many on Twitter are suggesting, that link makes two renowned researchers/commentators or here is Kai Kupferschmidt. I am less impressed by passing potshots at the author and more interested in reading a short blog post. I say write out 500 words (with links) comparing different methods of accounting for the unexplained residuals and heterogeneities with Covid-19 (not it is not all policy, and how much of it is sheer luck and/or timing?). Also discuss the circulating notion that previous exposure to (some) other coronaviruses, or perhaps weak doses of Covid-19, might be giving some individuals partial immunity (an idea being batted around but not verified as far as I know. And what do we know about how much geographic isolation might matter (a concept cited by Friston in contradistinction to the Twitter claims that he is simply talking about ghosts)? Then tweet the post, you still can start a blog for free and write just a single post, more over time if you wish. I would very gladly link to it.