It's pretty popularly thought right now that some very high % of the population must become infected to reach herd immunity (60-70%). The higher the R0, the greater number of people need to be infected to reach herd immunity.
So that is where the 60% number comes from. I believe the actual equation is 1-1/R0, and estimating R0 at 2.5 equals 60%. Estimating at 5.5 is >80%.
Why are few considering that every person has a distinct R0, and the average R0 isn't that relevant? Most people have a very low R0: most people see the same 5-10 people every day, and go home. If we use Pareto (80/20), you have 20% of the population who have high R0: they shake hands all day, they ride the subway, etc...
What is important is that super-spreaders be contained, not that everyone be contained (and, super spreader conditions be contained: mass indoor gatherings, namely). If super spreaders are contained, that average R0 goes way down. If R0 goes down to 1.5, 33% of the population needs to be exposed to achieve "herd immunity." R0 could be lower than that.
So that is where the 60% number comes from. I believe the actual equation is 1-1/R0, and estimating R0 at 2.5 equals 60%. Estimating at 5.5 is >80%.
Why are few considering that every person has a distinct R0, and the average R0 isn't that relevant? Most people have a very low R0: most people see the same 5-10 people every day, and go home. If we use Pareto (80/20), you have 20% of the population who have high R0: they shake hands all day, they ride the subway, etc...
What is important is that super-spreaders be contained, not that everyone be contained (and, super spreader conditions be contained: mass indoor gatherings, namely). If super spreaders are contained, that average R0 goes way down. If R0 goes down to 1.5, 33% of the population needs to be exposed to achieve "herd immunity." R0 could be lower than that.
