On 31 May, in an interview with The Guardian, Friston raised eyebrows by stating that the path of the epidemic in Germany could only be explained by some kind of “immunological dark matter.” “This is like dark matter in the universe,” he added. “We can’t see it, but we know it must be there to account for what we can see.” In several recent interviews, Friston elaborated only slightly. He doesn’t claim to know what the dark matter is. But he remains convinced that the models work only if there is some portion of the population who is, in his words, “out of the game.”
