Results from the initial primary analysis of the Novavax Covid-19 vaccine trial conducted by Wits VIDA in SA have been published.
The New England Journal of Medicine (NEJM) published findings of the Phase 2b clinical trial conducted in South Africa. NEJM is recognized as the world’s leading medical journal.
Shabir Madhi, Professor of Vaccinology, co-author of the study, and the Director of the Vaccines & Infectious Diseases Analytics Research Unit (Wits VIDA), led the Novavax Covid-19 vaccine trial in South Africa.
Publication of initial primary analysis highlights cross-protection by the Novavax Covid-19 vaccine against the B.1.351 variant prevalent in South Africa during the study.
This is the first published study to show protection against mild Covid-19 caused by the B.1.351 variant circulating in South Africa.
An updated analysis of the study indicated 100% protection against severe Covid-19 due to the B.1.351 variant.
“An efficacy of 50% is sufficient to meet the World Health Organization criteria for regulatory approval of the vaccine,” says Madhi.
The Novavax Covid-19 vaccine, known as NVX-CoV2373, is made by Novavax, Inc., a US-based biotechnology company developing next-generation vaccines for serious infectious diseases.
Gregory M. Glenn, M.D., President of Research and Development, Novavax, says: “This data publication reinforces the encouraging safety profile and cross-protective effect across variants seen in studies of our vaccine to-date.”
About the study
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 – i.e., the Novavax vaccine demonstrated an overall efficacy of 49% in the initial analysis (published in NEJM), and 49% in the subsequent complete analysis (unpublished).
Among healthy adults without HIV, the Novavax vaccine 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 that dominates in South Africa, and increasingly in southern Africa.
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.
“The data make a compelling case for use of the Novavax Covid-19 vaccine in settings where the B.1.351 variant dominates – which is most of southern Africa – to reduce the risk of mild disease and also to maximize the opportunity for protection against severe Covid,” says Madhi. “Further work is required for Novavax and all other Covid-19 vaccines, particularly in people living with HIV.”