effectiveness against infection and additionally whether an original booster dose was associated with increased protection beyond primary vaccination. This was achieved by comparing the odds of infection between boosted and booster-eligible people with and without a documented prior infection.
The researchers found that primary vaccination provided protection against omicron infection among people with and without a documented prior infection. While original booster vaccination was associated with additional protection against omicron infection in people without a documented prior infection, it was not found to be associated with additional protection among people with a documented prior infection.
The researchers emphasize that while the initial booster may not provide additional benefits in preventing omicron infection in some people, it still offers the best protection againstand hospitalization, according to previous studies. This study was limited to omicron infections and should be considered alongside other existing and future studies examining the relative benefits of booster doses against severe COVID-19 disease among people with and without prior infections.
Additionally, this analysis was conducted prior to the distribution of the bivalent COVID-19 booster and the findings are limited to associations between the original vaccines and omicron infection. Lind adds,"In this retrospective study, we found that primary mRNA vaccination provides moderate protection against omicron infection regardless of prior infection history. However, the relative benefits of an original booster dose against omicron infection may be affected by a person's history of prior SARS-CoV-2Association between primary or booster COVID-19 mRNA vaccination and Omicron lineage BA.