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VE is
calculated with this equation. Where ARU is the AR in unvaccinated and ARV
is the AR in the vaccinated. Thus vaccine efficacy is
If you divide the equation throughout by ARU, the result is 1 minus the relative risk, where RR is equal to ARV divided by ARU.
Thus VE
is also the
AS long as the AR in the vaccinated population is lower than the ARU - which you would expect - then RR will be less than one |