1/ I've been trying to understand how such "theorem" might have come into existence. The idea that our species is being invaded by a virus that is causing a lot of respiratory disease, much more fatal that common respiratory viruses, ...
2/ will only be sustainably controlled by herd immunity which is only achieved when 70% or more of the population is immune, is "absorbing". Letting the epidemic run its course unmitigated is of course unthinkable and, in the absence of effective treatments, ...
3/ the only option is to reduce transmission by means of non-pharmaceutical interventions (such as social distancing) until herd immunity is achieved, either naturally or by vaccination when scientists develop one (theorem).
4/ Ok, until we realise 70% of natural herd immunity may take 3 years to achieve while a vaccine may take more than 1 year and is uncertain. At this point we realise that there are other diseases and problems in our societies which have been aggravated by the pandemic response.
5/ Trade-offs become necessary and we begin to escape from that early absorbing state and the theorem about it. Due to individual variation some escape much faster than others generating the spectrum of positions we hear every day.
6/ Meanwhile some scientists (a very small number) have been saying all along that natural herd immunity in populations whose individuals differ in their susceptibility or exposure to infection might require only 20% of the population to be immune. ...
7/ Some populations are now reaching 20% seroprevalence (although tests are not perfect) and are experiencing sustained declines in new infections (even more so in deaths) despite some relaxation of social distancing measures.
8/ These reduced numbers make trade-off problems solvable and research incredibly rewarding. Yes, and the more efficiently we conduct this research the better our species will come out of this horrible crisis.
