Short-Term Relative Effectiveness of Homologous NVX-CoV2373 and BNT162b2 COVID-19 Vaccinations in South Korea

Abstract

To estimate the relative, short-term 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. 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, the aHR was 0.86 (95% CI: 0.82–0.91) for all laboratory-confirmed and 0.80 (95% CI: 0.48–1.33) for severe infections. Among homologous 1st-booster recipients, it was 0.74 (95% CI: 0.61–0.90) for all laboratory-confirmed and 0.48 (95% CI: 0.12–1.92) for severe infections. At 30-days post-immunization, we observed homologous, NVX-CoV2373 primary-series and 1st-booster offered added protection against SARS-CoV-2 infection versus BNT162b2; while there was numerically lower risk of severe disease among NVX-CoV2373-vaccinated, no statistically significant differences were observed.