Hybrid and natural immunity are robust but, like vaccine immunity, wane over time

Référence

Goldberg Y, Mandel M, Bar-on YM, et al. Protection and waning of natural and hybrid immunity to SARS-CoV-2. N Engl J Med 2022;386(23):2201-2212.

Sommaire

This study from the Israeli Ministry of Health used national data on infections during the delta wave of COVID-19 (August and September 2021) to compare 4 different kinds of immunity: (1) vaccination with 2 or 3 doses of the Pfizer/BioNTech vaccine, (2) recovery from COVID-19 infection, (3) recovery from COVID-19 followed by a single vaccine dose, and (4) a single vaccine dose followed by recovery from COVID-19. The primary outcome was the number of cases per 100,000 person-days of follow-up based on a Poisson regression model that adjusted for age, sex, and religious group (general Jewish, ultraorthodox Jewish, or Arab). Unvaccinated persons who had recovered from COVID-19 had good protection from subsequent infection, and it was actually better than that of those who had 2 vaccine doses at each time point (recall that unboosted individuals did not have much protection from infection with the delta variant). There was only limited follow-up for those with a single booster, but their protection was good out to 2 months. Those with hybrid immunity had impressive protection out to 8 months, without much difference depending on whether infection or vaccine came first. For example, at 4 to 6 months following infection or vaccine, the hybrid immunity and natural immunity groups had only 10 infections per 100,000 person-days compared with the 2-dose vaccine group which had 70 infections. The authors did not have much information on severe infections, and we don't know about the protection afforded by infection with the omicron variant.