Novavax’s COVID-19 vaccine 49 percent effective against B.1.351 variant

New data shows NVX-CoV2373 offered complete protection against severe COVID-19 and 60 percent efficacy against infection with the B.1.351 variant in healthy adults.

Close up of the gloved hands of a doctor drawing a vaccine dose into a syringe from a vial labelled 'COVID-19 VACCINE'

Results from an initial primary analysis of a Phase IIb trial evaluating Novavax’s NVX-CoV2373 COVID-19 vaccine candidate in South Africa show the vaccine is effective at preventing COVID-19 in this area, where the majority of cases are caused by the B.1.351 ‘escape variant’. The results were published in the New England Journal of Medicine (NEJM).

The Phase IIb randomised, observer-blinded, placebo-controlled trial evaluated the efficacy, safety and immunogenicity of NVX-CoV2373 in healthy adults and in a small cohort of medically stable adults living with human immunodeficiency virus (HIV). The study met its primary endpoint, with NVX-CoV2373 demonstrating an overall efficacy of 49 percent in the initial analysis (published in NEJM) and 49 percent in the subsequent complete analysis (unpublished).

In healthy adults (without HIV), NVX-CoV2373 demonstrated efficacy of 60 percent in the initial analysis and 55 percent 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. As such, the company stated that NVX-CoV2373 offers complete protection against severe disease.

The initial analysis 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 because at 90 days of follow-up, among placebo recipients, the illness rate was eight percent in baseline seronegative participants and 5.9 percent in baseline seropositive participants.

“This data publication reinforces the encouraging safety profile and cross-protective effect across variants seen in studies of our vaccine to-date,” stated Dr Gregory Glenn, 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.” SARS-CoV-2 is the virus that causes COVID-19.

NVX-CoV2373 is being evaluated in two pivotal Phase 3 trials: a trial in the U.K. that demonstrated 100% protection against severe disease, efficacy of 96.4% against the original virus strain, 86.3% against the B.1.1.7/501Y.V1 variant and 89.7% overall; and the PREVENT-19 trial in the U.S. and Mexico that began in December 2020. It is also being tested in two ongoing Phase 2 studies that began in August 2020: A Phase 2b trial in South Africa that demonstrated 100% protection against severe disease and 48.6% efficacy against a newly emerging escape variant first described in South Africa, and a Phase 1/2 continuation in the U.S. and Australia.