AI Article Synopsis
- The study evaluates the effectiveness of a third booster dose of the Pfizer-BioNTech vaccine (BNT162b2) among adults in the U.S., finding that while the effectiveness of two doses declines over time, a third dose significantly boosts protection against both SARS-CoV-2 infections and hospitalizations.
- In two doses, vaccine effectiveness against infections dropped from 85% to 49% over seven months, but the three-dose regimen exhibited 88% effectiveness against infections and 97% against hospitalization shortly after administration.
- The findings support booster recommendations as they show that a third dose provides enhanced protection compared to just two doses received months earlier.
Article Abstract
Background: Globally, recommendations are expanding for third (booster) doses of BNT162b2 (Pfizer-BioNTech). In the United States, as of November 19, 2021, boosters were recommended for all adults aged 18 years and older. We evaluated the effectiveness of a third dose of BNT162b2 among adults in a large US integrated health system.
Methods: In this retrospective cohort study, we analyzed electronic health records from Kaiser Permanente Southern California between Dec 14, 2020 and Dec 5, 2021 to assess vaccine effectiveness (VE) of two and three doses of BNT162b2 against SARS-CoV-2 infections (without hospital admission) andCOVID-19-related hospital admission. VE was calculated using hazards ratios from adjusted Cox models.
Findings: After only two doses, VE against infection declined from 85% (95% CI 83-86) during the first month to 49% (46-51) ≥ 7 months following vaccination. Overall VE against hospitalization was 90% (95% CI 86-92) within one month and did not wane, however, effectiveness against hospitalization appeared to wane among immunocompromised individuals but was not statistically significant (93% [72-98] at 1 month to 74% [45-88] after ≥ 7 months; p=0·490). Three-dose VE (median follow-up 1·3 months [SD 0·6]) was 88% (95% CI 86-89) against infection and 97% (95-98) against hospitalization. Effectiveness after three doses was higher than that seen one month after receiving only two doses for both outcomes. Relative VE of three doses compared to two (with at least six months after the second dose) was 75% (95% CI 71-78) against infections and 70% (48-83) against hospital admissions.
Interpretation: These data support the benefit of broad BNT162b2 booster recommendations, as three doses confers comparable, if not better, protection against SARS-CoV-2 infections and hospital admission as was seen soon after receiving two doses.
Funding: Pfizer Inc.
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Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8841530 | PMC |
| http://dx.doi.org/10.1016/j.lana.2022.100198 | DOI Listing |
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