Statistically a disease reaches herd immunity if everyone except 1 / R0 are infected.
For a disease with R0 of 3 (such as covid) this would be 66%. To explain: If two out of three are immune then a disease which usually infects three people will run out of steam.
For a disease with R0 of 3 (such as covid) this would be 66%. To explain: If two out of three are immune then a disease which usually infects three people will run out of steam.