Dödligt virus från Kina orsakar panik (SARS-CoV-2, COVID-19)

Now, from the unlikely source of a prominent member of the “Independent SAGE committee”, the group set up by Sir David King to challenge government scientific advice and accused by some of being populated with Left-wing activists, comes a claim that the true portion of people who are not even susceptible to Covid-19 may be as high as 80%.

Professor Karl Friston, like Michael Levitt, is a statistician not a virologist; his expertise is in understanding complex and dynamic biological processes by representing them in mathematical models. Within the neuroscience field he was ranked by Science magazine as the most influential in the world, having invented the now standard “statistical parametric mapping” technique for understanding brain imaging — and for the past months he has been applying his particular method of Bayesian analysis, which he calls “dynamic causal modelling”, to the available Covid-19 data.

Friston referred to some kind of “immunological dark matter” as the only plausible explanation for the huge disparity in results between countries in an interview with the Guardian last weekend. The eye-catching phrase attracted a lot of attention on social media, with some commentators keen to dismiss it as rubbish, but he meant it in a quite precise way: like dark matter, the undetectable substance that makes up approximately 85% of the universe, it is provably there by its effects. We just don’t know anything about it.