New England Journal of Medicine Publishes Phase 2b Clinical Trial Results Demonstrating Efficacy of Novavax COVID-19 Vaccine Against the B.1.351 Variant

Novavax, Inc. a biotechnology company developing next-generation vaccines for serious infectious diseases, announced the publication of results from the initial primary analysis of a Phase 2b clinical trial conducted in South Africa of its NVX-CoV2373 COVID-19 vaccine candidate in the New England Journal of Medicine (NEJM). The published data provide additional detail of an initial analysis conducted in January, while more robust data from a complete analysis of the study was subsequently shared in March 2021. The data on the initial analysis will be published online ahead of print in NEJM’s May 6, 2021 issue.

“This data publication reinforces the encouraging safety profile and cross-protective effect across variants seen in studies of our vaccine to-date,” said Gregory M. Glenn, M.D., President of Research and Development, Novavax. “It also demonstrates that ongoing evaluation of COVID-19 vaccine efficacy against SARS-CoV-2 variants is urgently needed to inform vaccine development and use.”

The Phase 2b randomized, observer-blinded, placebo-controlled trial conducted in South Africa evaluated efficacy, safety and immunogenicity in healthy adults, and in a small cohort of medically stable adults living with human immunodeficiency virus (HIV). The study met its primary endpoint. NVX-CoV2373 demonstrated an overall efficacy of 49% in the initial analysis (published NEJM), and 49% in the subsequent complete analysis (unpublished). Among healthy adults without HIV, NVX-CoV2373 demonstrated efficacy of 60% in the initial analysis and 55% in the subsequent complete analysis. In the initial analysis, cases were predominantly mild-to-moderate and due to the B.1.351 variant. In the subsequent complete analysis, circulation of the B.1.351 variant continued to dominate, and all five cases of severe disease observed in the trial occurred in the placebo group.

The initial analysis, now being published in NEJM, suggested that prior infection with the original COVID-19 strain did not protect against subsequent infection by the variant predominantly circulating in South Africa through 60 days of follow-up. However, with additional follow-up, the complete analysis of the South Africa trial indicates that there may be a modest protective effect of prior exposure with the original COVID-19 strain. Among placebo recipients, at 90 days of follow-up, the illness rate was 8.0% in baseline seronegative participants and 5.9% in baseline seropositive participants.