ABSTRACT
Background/ObjectivesCOVID-19 continues to pose a significant burden that impacts public health and the healthcare system as the SARS-CoV-2 virus continues to evolve. Regularly updated vaccines are anticipated to boost waning immunity and provide protection against circulating variants. This study evaluated vaccine effectiveness (VE) of mRNA-1273.815, a 2023-2024 Omicron XBB.1.5-containing mRNA COVID-19 vaccine, at preventing COVID-19-related hospitalizations and any medically attended COVID-19 in adults [≥]18 years, overall, and by age and underlying medical conditions. MethodsThis retrospective cohort study used the Veradigm Network EHR linked to claims data to identify US adults [≥]18 years of age who received the mRNA-1273.815 vaccine (exposed) matched 1:1 to individuals who did not receive a 2023-2024 updated COVID-19 vaccine (unexposed). Patients in the unexposed cohort were randomly matched to eligible mRNA-1273.815 recipients. Inverse probability of treatment weighting was used to adjust for differences between the two cohorts. The exposed cohort was vaccinated between September 12, 2023, and December 15, 2023, and individuals in both cohorts were followed up for COVID-19-related hospitalizations and medically attended COVID-19 until December 31, 2023. A Cox regression model was used to estimate the hazard ratio (HR). VE of the mRNA-1273.815 vaccine in preventing COVID-19-related hospitalizations and any medically attended COVID-19 was estimated as 100*(1-HR). Subgroup analyses were performed for adults [≥]50, adults [≥]65, and individuals with underlying medical conditions associated with severe COVID-19 outcomes. ResultsOverall, 859,335 matched pairs of mRNA-1273.815 recipients and unexposed adults were identified. The mean age was 63 years, and 80% of the study population was [≥]50 years old. 61.5% of the mRNA-1273.815 cohort and 66.4% of the unexposed cohort had an underlying medical condition. Among the overall adult population ([≥]18 years), VE was 60.2% (53.4-66.0%) against COVID-19-related hospitalization and 33.1% (30.2%-35.9%) against medically attended COVID-19 over a median follow-up of 63 (IQR: 44-78) days. VE estimates by age and underlying medical conditions were similar. ConclusionsThese results demonstrate the significant protection provided by mRNA-1273.815 against COVID-19-related hospitalizations and any medically attended COVID-19 in adults 18 years and older, regardless of their vaccination history, and support CDC recommendations for vaccination with the 2023-2024 Omicron XBB.1.5-containing COVID-19 vaccine to prevent COVID-19-related outcomes, including hospitalizations.
Subject(s)
COVID-19ABSTRACT
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