Fully Vaccinated: 132,769,894
33,989,237 documented as having been infected by Covid-19
Total vaccinated and infected: 166,769,131 = 50% of total population
Do we have herd immunity yet?
“Do we have herd immunity yet?”
I contend that we started seeing Herd Immunity effects on the case numbers in mid-April.
It is not like a sudden total on-off switch - it bends the curve downward. It is continuing to strengthen, and more strongly suppress the disease, as more and more people develop immunity.
There is difference in replication rates (Ro), among the variants - some are more infectious (not necessarily more deadly, just spread more easily). 60% of adults was calculated as the Herd Immunity Threshold (HIT) for the original variant (1 - 1/Ro). We are pretty much there now just with first shots.
Of course, as you point out, those with immunity from exposure also count. We know how many popped positive on tests, and there is also some number that had it, but were not tested.
Some of the variants require almost 80% for HIT.
But we are in the window already, where the high number with immunity is degrading the virus’ ability to increase in the population. It is probably a factor in the changing variant mix, as some less infectious variants are likely already getting choked out.