Effectiveness of NVX-CoV2373 and BNT162b2 COVID-19 Vaccination in South Korean Adolescents

Purpose Adolescents can have severe/chronic outcomes from COVID-19. Real-word data on relative vaccine effectiveness (rVE) between mRNA- and protein-based vaccines are limited, and more data are needed on disease outcomes in this age group.

The K-COV-N database, COVID-19 vaccine registry, and health insurance claims were retrospectively reviewed to identify adolescents (12–18-year-olds) in South Korea who received a homologous primary series of NVX-CoV2373 or BNT162b2 and a heterologous or homologous third vaccine dose. Vaccine recipients were propensity score matched to reduce confounding baseline factors. Adjusted hazard ratios (aHRs) for any medically attended COVID- 19 post vaccination (starting 14 days post primary series and 7 days post third dose) were calculated to assess rVE every 30 days through a 180-day risk window.

From February to December 2022, 3174 and 6253 doses of NVX-CoV2373 and BNT162b2, respectively, were administered to South Korean adolescents. Individuals who received NVX-CoV2373 tended to be older, have a disability, and/or have a prior SARS-CoV-2 infection. Propensity score matching resulted in 107 individuals in each primary series group and 701 and 1417 individuals in the NVX-CoV2373 and BNT162b2 third-dose groups, respectively. The aHR (95% CI) for NVX-CoV2373 compared with BNT162b2 for medically attended COVID-19 in the 180-day risk window was 0.57 (0.31–1.05) for the primary series and 0.68 (0.54–0.84) for the third dose.

These results suggest that NVX-CoV2373 may provide more robust protection against medically attended COVID-19, compared to BNT162b2, both as a homologous primary series and as a homologous or heterologous third dose. Implications and Contributions This study provides essential data on the real-world effectiveness of a protein-based (NVX- CoV2373) and an mRNA-based (BNT162b2) COVID-19 vaccine in adolescents. A homologous primary series and homologous/heterologous third dose of NVX-CoV2373 provided more robust protection than BNT162b2 at preventing medically attended COVID-19, with protection demonstrated through 6 months post vaccination. Competing Interest Statement E.G., S.-A.C., K.K., E.B., and Y.J.C. are study investigators and do not have any conflicts of interest to report. M.H.G., J.F., and M.D.R. are salaried employees of and may own stock in Novavax, Inc. M.V. was a salaried employee of Novavax, Inc., and may own stock. Funding Statement The study was funded by Novavax, Inc. Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study received ethical approval from the Korea University Anam Hospital institutional review board (IRB No. 2023AN0124). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Data Availability The data used in this study are from the K-CoV-N cohort, which is not publicly available. Researchers can apply for access to these data through the National Health Insurance Service (NHIS) and Korea Disease Control and Prevention (KDCA) data linkage system. Applications can be submitted via the Health Care Data Linkage (HCDL) website (https://hcdl.mohw.go.kr/) and are subject to review by the relevant authorities.