Comparative effectiveness of mRNA-1273 and BNT162b2 against symptomatic SARS-CoV-2 infection

mRNA coronavirus disease 2019 (COVID-19) vaccines are safe and effective, but increasing reports of breakthrough infections highlight the need to vigilantly monitor and compare the effectiveness of these vaccines. We retrospectively compared protection against symptomatic infection conferred by mRNA-1273 and BNT162b2 at Mayo Clinic sites from December 2020 to September 2021. We used a test-negative case-control design to estimate vaccine effectiveness (VE) and to compare the odds of symptomatic infection after full vaccination with mRNA-1273 versus BNT162b2, while adjusting for age, sex, race, ethnicity, geography, comorbidities, and calendar time of vaccination and testing. Both vaccines were highly effective over the study duration (VEmRNA-1273: 84.1%, 95% confidence interval [CI]: 81.6%–86.2%; VEBNT162b2: 75.6%, 95% CI: 72.2%–78.7%), but their effectiveness was reduced during July–September (VEmRNA-1273: 75.6%, 95% CI: 70.1%–80%; VEBNT162b2: 63.5%, 95% CI: 55.8%–69.9%) as compared to December–May (VEmRNA-1273: 93.7%, 95% CI: 90.4%–95.9%; VEBNT162b2: 85.7%, 95% CI: 81.4%–88.9%). Adjusted for demographic characteristics, clinical comorbidities, time of vaccination, and time of testing, the odds of experiencing a symptomatic breakthrough infection were lower after full vaccination with mRNA-1273 than with BNT162b2 (odds ratio: 0.60; 95% CI: 0.55–0.67). Both mRNA-1273 and BNT162b2 strongly protect against symptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. It is imperative to continue monitoring and comparing available vaccines over time and with respect to emerging variants to inform public and global health decisions. This study was funded by nference. [Display omitted] Both BNT162b2 and mRNA-1273 were highly effective against COVID-19Both vaccines were less effective after July as compared to before May 2021mRNA-1273 recipients had lower odds of COVID-19 than BNT162b2 recipientsmRNA-1273 recipients had a lower COVID-19 incidence rate than BNT162b2 recipients This is a study comparing the effectiveness of the mRNA coronavirus disease 2019 (COVID-19) vaccines developed by Pfizer/BioNTech and Moderna. Although it is well established that both vaccines are safe and effective, it is important to evaluate their effectiveness over time and relative to each other. The results from this study show that both of these vaccines have been effective in reducing the risk of COVID-19, although recipients of the Moderna vaccine were less l