Comparative effectiveness of mRNA-1273 and BNT162b2 against symptomatic SARS-CoV-2 infection.
Level 4 - case-series / case-control
Test-negative case-control study evaluating comparative vaccine effectiveness
PubMed 34927113 · doi:10.1016/j.medj.2021.12.002
What was done
Researchers performed a retrospective test-negative case-control study using electronic health records from Mayo Clinic sites between December 2020 and September 2021. They evaluated vaccine effectiveness (VE) against symptomatic SARS-CoV-2 infection and compared the odds of breakthrough infection between fully vaccinated recipients of mRNA-1273 and BNT162b2, adjusting for age, sex, race, ethnicity, geographic location, comorbidities, and calendar timing of vaccination and testing.
What was found
Overall vaccine effectiveness over the study period was 84.1% (95% CI: 81.6%–86.2%) for mRNA-1273 and 75.6% (95% CI: 72.2%–78.7%) for BNT162b2. Both vaccines showed waning or reduced effectiveness in July–September 2021 (mRNA-1273: 75.6%, 95% CI: 70.1%–80%; BNT162b2: 63.5%, 95% CI: 55.8%–69.9%) compared to December 2020–May 2021 (mRNA-1273: 93.7%, 95% CI: 90.4%–95.9%; BNT162b2: 85.7%, 95% CI: 81.4%–88.9%). Adjusted odds of symptomatic breakthrough infection were lower with mRNA-1273 than BNT162b2 (odds ratio: 0.60; 95% CI: 0.55–0.67).
Why it matters
This direct comparative analysis shows that while both mRNA platforms provide robust protection against symptomatic infection, mRNA-1273 exhibited moderately higher effectiveness and lower breakthrough rates across study periods.
Limits
The total sample size (number of cases and controls) is not reported in the abstract. As a retrospective observational design, potential residual confounding and healthcare-seeking biases cannot be completely excluded, and severe clinical outcomes (e.g., hospitalization or mortality) were not described.
Cited by
- context A multi-state Mayo Clinic study comparing 25,000 vaccinated and 25,000 unvaccinated individuals found that Pfizer vaccine efficacy against infection dropped from 88–93% down to 41% after the Delta variant became dominant.