Originally Posted by DeltaboundRedux
Something like 70-80% of the population will need to be vaccinated before any herd immunity takes effect.
Consideration must be given to immunity obtained by previous infection.
Sure infection-conferred immunity is fleeting (6-9 months by most estimates) and those people will eventually need to be vaccinated, but it will still have a multiplying impact on vaccinations reducing vectors for spread in the near-to-medium term. Enough to achieve herd immunity? Likely not. Enough to begin seeing sizable reductions in confirmed positive cases even as vaccination scales up in the next month or two? Absolutely.
Today's CDC update shows 21.26M confirmed positive cases in the US. The CDC's estimate for actual infections is 8 for every confirmed positive case, which estimates actual SARS-CoV-2 infections at 170M people...more than half the US population. Even if we assume that estimate is overly high, we're still almost certainly at a third of the US population previously infected and that will absolutely help bring down infections (and corresponding hospital admissions, ICU admissions and death) much earlier than achieving a 70%+ vaccination rate.