ABSTRACT
Background: The emergence of Omicron variants coincided with declining vaccine-induced protection against SARS-CoV-2 infection and other COVID-19-related outcomes. Two bivalent mRNA vaccines, mRNA-1273.222 (Moderna) and BNT162b2 Bivalent (Pfizer-BioNTech) were developed to provide greater protection against the predominate circulating variants by including the mRNA that encodes both the ancestral (original) strain and BA.4/BA.5. We estimated their relative vaccine effectiveness (rVE) in preventing COVID-19-related outcomes in the US. Methods: We conducted a retrospective cohort study using a US nationwide dataset linking primary care electronic health records (EHR) and pharmacy/medical claims data. The adult study population (aged >18 years) received either mRNA-1273.222 or BNT162b2 Bivalent vaccination between August 31, 2022, and February 28, 2023. We used a propensity score weighting based on the inverse probability of treatment to adjust for the baseline differences in age, sex, race, ethnicity, geographic region, vaccination week, and health status between groups. Outcomes evaluated were rVE of the two bivalent mRNA vaccines against COVID-19-related hospitalizations (primary outcome) and outpatient visits (secondary). We weighted the vaccine groups prior to analysis and estimated adjusted hazard ratios (HR) using multivariable Cox regression models. We calculated rVE as (1-HR) X 100. Results: We evaluated outcomes for 1,034,538 mRNA-1273.222 and 1,670,666 BNT162b2 Bivalent vaccine recipients. The adjusted rVE of mRNA-1273.222 versus BNT162b2 Bivalent vaccines against COVID-19-related hospitalization was 9.8% (95% confidence interval: 2.6% --16.4%). The adjusted rVE against COVID-19-related outpatient visits was 5.1% (95% CI: 3.2% --6.9%). When evaluated by age group, the incremental relative effectiveness was greater. Among adults [≥]65, rVE against COVID-19-related hospitalizations and outpatient visits was 13.5% (95% CI: 5.5% -- 20.8%) and 10.7% (8.2% -- 13.1%), respectively. Conclusion: We found greater effectiveness of mRNA-1273.222 compared with the BNT162b2 Bivalent vaccine in preventing COVID-19-related hospitalizations and outpatient visits, with increased benefits in older adults
Subject(s)
COVID-19ABSTRACT
Background: Few head-to-head comparisons have been performed on the real-world effectiveness of COVID-19 booster vaccines. We evaluated the relative effectiveness (rVE) of a primary series of mRNA-1273 versus BNT162b2 and Ad26.COV2.S and a homologous mRNA booster against medically-attended, outpatient, and hospitalized COVID-19. Methods: A dataset linking primary care electronic medical records with medical claims data was used for this retrospective cohort study of US patients [≥]18 years vaccinated with a primary series between February and October 2021 (Part 1) and a homologous mRNA booster between October 2021 and January 2022 (Part 2). Adjusted hazard ratios (HR) were derived from 1:1 matching adjusted across potential covariates. rVE was (1-HRadjusted) x 100. Additional analysis was performed across regions and age groups. Results: Following adjustment, Part 1 rVE for mRNA-1273 versus BNT162b2 was 23% (95% CI: 22%-25%), 23% (22%-25%), and 19% (14%-24%) whilst the rVE for mRNA-1273 versus Ad26.COV2.S was 50% (48%-51%), 50% (48%-52%), and 57% (53%-61%) against any medically-attended, outpatient, and hospitalized COVID-19, respectively. The adjusted rVE in Part 2 for mRNA-1273 versus BNT162b2 was 14% (10%-18%), 13% (8%-17%), and 19% (1%-34%) against any medically-attended, outpatient, and hospitalized COVID-19, respectively. rVE against medically-attended COVID-19 was higher in adults [≥]65 years (35%; 24%-47%) than those 18-64 years (13%; 9%-17%) after the booster. Conclusions: In this study, mRNA-1273 was more effective than BNT162b2 or Ad26.COV2.S following primary series during a Delta-dominant period, and than BNT162b2 as a booster during an Omicron-dominant period.