Vaccination, Previous Infection, or Both: Which Confers the Most Durable Protection Against Subsequent SARS-CoV-2 Infection?

Comparing the effects of previous COVID-19, vaccination, or a blend of both factors on risk for subsequent infection suggests a potential advantage to hybrid immunity. Using Israeli national data on vaccination with BNT162b2 (Pfizer-BioNTech), investigators evaluated risk for infection during the Delta wave (August 1–September 30, 2021) by preexisting immunity categorized as: (a) recovered and unvaccinated, (b) recovered and vaccinated with one dose, (c) vaccinated with one dose and recovered, (d) vaccinated with two doses, and (e) vaccinated with three doses. Risk for infection was analyzed by time since the immunity-conferring event.

The adjusted rate of reinfection in the recovered, unvaccinated cohort rose from 10.5 per 100,000 person-da…