COVID-19 Immunity Enhanced After Boosting

The peer-reviewed journal Annuals of Internal Medicine today published Original Research from the largest real-world observational study that concluded 'persons previously infected with the SARS-CoV-2 virus gained additional protection against reinfection and COVID-19 from a subsequent single dose of the Pfizer - BioNTech (Comirnaty, BNT162b2) vaccine.'

Nonetheless, 'even without a subsequent COVID-19 vaccination, virus reinfection appeared relatively rare.'

This retrospective study, published on February 15, 2022, found a statistically significant decreased risk (hazard ratio, 0.18 [95% CI, 0.15 to 0.20]) for reinfection was found among previously infected persons and then vaccinated versus those who were previously infected but remained unvaccinated.

In addition, there was a decreased risk for symptomatic disease (hazard ratio, 0.24 [CI, 0.20 to 0.29]) among previously infected and vaccinated persons compared with those who were not immunized after infection between March and December 13, 2021.

This finding supports previous small cohort studies pointing to evidence of a boosting effect of neutralizing antibody activity, or an anamnestic response, in previously infected persons receiving a single dose of an mRNA vaccine, as well as SARS-CoV-2–specific T-cell and memory B-cell response and affinity maturation.

Hybrid protection against non-Delta variants could not be inferred in this study.

The data source was a nationally centralized database of Maccabi Healthcare Services, Israel. No industry-related conflicts of interest were disclosed.

Additional immunity research is published at PrecisionVaccinations/immunity.