Relative effectiveness of homologous NVX-CoV2373 and BNT162b2 COVID-19 vaccinations in South Korea

To estimate the relative effectiveness of NVX-CoV2373 versus BNT162b2 (Pfizer-BioNTech) in preventing SARS-CoV-2 infection and severe COVID-19 disease during the Omicron variant dominance in South Korea, we conducted a retrospective cohort-study among ≥12-year-olds using the K-COV-N database, which links COVID-19 vaccine registry data with health insurance claims data. The Cox proportional-hazards model and inverse probability of treatment weighting were employed to calculate adjusted hazard ratios (aHRs). Among homologous primary-series NVX-CoV2373 versus BNT162b2 recipients at Day 180 post-vaccination, the aHR was 0.90 (95% CI: 0.87-0.93) for all laboratory-confirmed and 0.65 (95% CI: 0.48-0.88) for severe infections. Among homologous 1st-booster recipients, it was 1.15 (95% CI: 1.01-1.30) for all laboratory-confirmed and 0.39 (95% CI: 0.20-0.75) for severe infections. At 180-days post-immunization, we observed homologous, NVX-CoV2373 primary-series added and 1st booster offered comparable protection against SARS-CoV-2 infection versus BNT162b2.