But the effect of natural immunity is all around us. Stated target of 70% to 85% of the population becoming immune through full vaccination. Without accounting for natural immunity, we are far from In public health, we call that herd immunity, defined broadly on the Johns Hopkins Covid information webpage as “when most of a population is immune.” It’s not eradication, but it’s powerful. With more than 8 in 10 adults protected from either contracting or transmitting the virus, it can’t readily propagate by jumping around in the population. The contribution of natural immunity should speed up the timeline for returning fully to normal. That share necessarily increased as the pandemic spread. A similar study, by the University of Albany and New York State Department of Health, revealed that by the end of March 2020-the first month of New York’s pandemic-23% of the city’s population had antibodies. A February study in Nature used antibody screenings in late summer 2020 to estimate there had been seven times as many actual cases as confirmed cases. Only around 10% of Americans have had confirmed positive Covid tests, but four to six times as many have likely had the infection.