Vaccination Tipping Point for COVID-19

Before a population can reach herd immunity, an inflection point has to occur — the point where there’s enough immunity, through vaccination and previous infection, that cases begin to decline consistently. Experts suspect the United States hit an inflection point in late April. Cases may continue to steadily decline, especially as vaccination rates increase. When we talk about building enough immunity in the population to blunt the spread of COVID-19, we usually refer to herd immunity. Herd immunity prevents community transmission of disease when about 70 percent of the population is immune (either through vaccination or previous infection). But before a population reaches herd immunity, an inflection point must occur — the point where there’s enough immunity that cases begin to decline consistently. Israel, for example, hit an inflection point in early March when about 40 percent of the population was given the first dose of the COVID-19 vaccine. Some experts think the United States hit its inflection point in late April when, similarly, 40 percent of the population received at least one dose. Cases have been declining since