Work out vaccine coverage requirement instantly with clear inputs, formula shown and shareable results.
Works out the coverage needed to reach the herd immunity threshold given vaccine efficacy, and shows the effective reproduction number at current coverage.
Coverage requirement
Required coverage = (1 - 1/R0) / vaccine efficacy; effective immunity = coverage x efficacy; Rt = R0 x (1 - effective immunity)
An imperfect vaccine protects only a share of those vaccinated, so immunity equals coverage times efficacy.
Yes. Waning immunity and birth cohorts continually add susceptibles, which is why coverage must be sustained.