Good epidemiological study- herd immunity at 40 %
Herd immunity at 40 %? This study does not consider the XYZ hypothesis of Chris, so in reality, it can be a lot lower.
It makes a model of 2 populations, with very different R0:
– The younger active population, with a high transmission rate of the virus, but a low morbidity/mortality.
– An older, more vulnerable population which is much more careful and protected (low transmission rate, high morbidity/ mortality).
Population 1 obtains herd immunity rather quickly, and has limited interaction with population 2. In due time, the highly infective population is eliminated as a threat, and the R0 of the total population falls below 1. Cluster outbreaks and superspread events can still happen in population 2.
This model includes the factor ‘percolation’, the amount of exchange between the populations. Measures should be concentrated on this factor.
In reality many more populations exist, and many percolation factors, like air travel, etc. But I think this study is a step forward in epideomological thinking.
It seems the link did not work: