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Effectiveness of BNT162b2 BA.4/5 Bivalent mRNA Vaccine Against Symptomatic COVID-19 Among Immunocompetent Individuals
Abby E Rudolph1, Farid L Khan1, Amy Shah2
1Pfizer, Collegeville, Pennsylvania, USA.
Background:
Data on the effectiveness of BA.4/5 bivalent vaccine stratified by age and prior infection are lacking.
Methods:
This test-negative study used data from individuals ≥5 years of age testing for SARS-CoV-2 with symptoms (15 September 2022 to 31 January 2023) at a large national retail pharmacy chain. The exposure was receipt of 2-4 wild-type doses and a BNT162b2 BA.4/5 bivalent vaccine (>2 months since last wild-type dose). The outcome was a positive SARS-CoV-2 test. Absolute (vs unvaccinated) and relative (vs 2-4 wild-type doses) vaccine effectiveness (VE) were calculated as (1 - adjusted odds ratio from logistic regression) × 100. VE was stratified by age and self-reported prior infection.
Results:
Overall, 307 885 SARS-CoV-2 tests were included (7916 aged 5-11, 16 329 aged 12-17, and 283 640 aged ≥18 years). SARS-CoV-2 positivity was 39%; 21% were unvaccinated, 70% received 2-4 wild-type doses with no bivalent vaccine, and 9% received a BNT162b2 BA.4/5 bivalent dose. At a median of 1-2 months after BNT162b2 BA.4/5 bivalent vaccination, depending on age group, absolute VE was 22%-60% and was significantly higher among those reporting prior infection (range, 55%-79%) than not (range, no protection to 50%). Relative VE was 31%-64%.
Conclusions:
BNT162b2 BA.4/5 bivalent showed early additional protection against Omicron-related symptomatic COVID-19, with hybrid immunity offering greater protection.
