[jfoster]

Very difficult to get herd immunity up to a decent enough level without putting the vulnerable portion of the population in great danger though. Most countries are approaching something like 0.1% or 0.2% of the population having been infected. Herd immunity requires 70% - 80% immunity. About 350x - 800x more than what's happened already.

Also the whole thing presumes that immunity is lasting. Some of the data is showing that may not be the case.

[danieltillett]

The level of herd immunity needed is related to the R0 which is a function of behaviour. This is a really complex topic to discuss, but it is only one we can have once an attenuated strain is found.

Of course the other factor is who is a vulnerable person is a factor of the pathogenicity of the viral strain.