BACKGROUND: Although several COVID-19 vaccines are approved or authorized in the United States (US), early real-world studies have shown waning vaccine effectiveness (VE) against SARS-CoV-2 infection over time. Changes in circulating variants may also complicate assessments of waning VE over time.
OBJECTIVES: We evaluated the overall VE and VE over time of receiving a complete primary series for the first 3 US-approved/authorized monovalent COVID-19 vaccines—BNT162b2 (Pfizer-BioNTech), mRNA-1273 (Moderna), and JNJ-7836735 (Janssen)—in adults (18-64 years).
METHODS: Using data from 2 US health insurance claims databases (Optum, CVS Health) and Immunization Information Systems (study period 11 December 2020 to 15 January 2022 [Optum] and 11 December 2020 to 31 March 2022 [CVS Health]), we identified vaccinated individuals at their first dose and matched them to unvaccinated comparators on calendar date and personal characteristics to reduce selection bias, immortal person-time bias, and confounding. Follow-up began on the dose 1 or matching date; the vaccinated group was censored if they failed to receive a complete primary series. We estimated VE overall and by time since vaccination with 95% confidence intervals (CIs) against COVID-19 diagnosis from any medically attended setting, or specifically from a hospital/emergency department (ED). Analyses were performed separately by data source and meta-analyzed. We also estimated VE in different variant eras (pre-Delta, Delta, Omicron), and compared VE between vaccine brands.
RESULTS: The cohorts consisted of 341,097 (Optum) and 1,151,775 (CVS) matched pairs for BNT162b2; 201,604 (Optum) and 651,545 (CVS) for mRNA-1273; and 49,285 (Optum) and 149,813 (CVS) for JNJ-7836735. Meta-analyzed overall VE estimates against medically diagnosed and hospital/ED-diagnosed (respectively) COVID-19 for BNT162b2 were 50% (95% CI, 50%-51%) and 77% (95% CI, 76%-78%); for mRNA-1273, 59% (95% CI, 58%-60%) and 84% (95% CI, 83%-85%); and for JNJ-7836735, 38% (95% CI, 36%-40%) and 66% (95% CI, 63%-68%). VE estimates were generally sustained for approximately 200 days for medically diagnosed COVID-19 and 300 days for hospital/ED-diagnosed COVID-19 before waning. Overall VE estimates were highest for mRNA-1273, and era-specific VE was lowest during the Omicron era.
CONCLUSIONS: Observed VE estimates for all brands indicated the vaccines were protective against COVID-19 and that effectiveness was sustained for at least 7 months. VE estimates were higher for hospital/ED-diagnosed COVID-19 than for any medically diagnosed COVID-19 and were highest in adults receiving mRNA-1273. In the rapidly changing dynamics of the COVID-19 pandemic, additional real-world research is needed as new variants emerge and vaccines are updated.
