Novavax, a U.S.-based biotechnology company developing a recombinant vaccine for COVID-19, announced a final efficacy of 96.4% against mild, moderate and severe disease caused by the original SARS-CoV-2 strain in a pivotal Phase 3 trial in the United Kingdom (U.K.).
In January, the company reported that its vaccine had proved to have 89% efficacy in preventing the infection in some trial volunteers in the United Kingdom.
The Serum Institute of India has an agreement with Novavax to manufacture several doses.
It is likely to conduct a bridging study (that determines the vaccine’s safety and immunogenicity in Indians).
Novavax in January also reported results of a trial in South Africa, testing the vaccine in two groups of healthy individuals as well as a small group of 245 individuals who were HIV positive and medically stable. Overall, the efficacy was 48.6% — a result, the company says, was due to the pre-dominance of the variant ‘South African’ strain, B.1.351/501Y.V2. In just the HIV group alone, the efficacy was 55%. Across both trials, NVX-CoV2373 demonstrated 100% protection against severe disease, including all hospitalisation and death.
“We are very encouraged by the data showing that NVX-CoV2373 not only provided complete protection against the most severe forms of disease, but also dramatically reduced mild and moderate disease across both trials. Importantly, both studies confirmed efficacy against the variant strains,” Stanley C. Erck, President and Chief Executive Officer, Novavax, said in a statement.
In the UK trial, the study enrolled more than 15,000 participants between 18-84 years of age, including 27% over the age of 65. The primary endpoint of the U.K. Phase 3 clinical trial was based on the first occurrence of PCR-confirmed symptomatic (mild, moderate or severe) COVID-19 with onset at least 7 days after the second study vaccination in serologically negative (to SARS-CoV-2) adult participants at baseline.
Efficacy was 96.4% (95% CI: 73.8, 99.5) against the original virus strain and 86.3% (95% CI: 71.3, 93.5) against the B.1.1.7/501Y.V1 variant, or the so called UK variant.
Five severe cases were observed in the study, and all occurred in the placebo group. Four of the five severe cases were attributed to the B.1.1.7/501Y.V1 variant.
An analysis of trial results by the company in January had suggested that prior infection with the original COVID-19 strain might not completely protect against subsequent infection by the variant predominantly circulating in South Africa. However, the complete analysis of the South Africa trial indicates that there could be a late protective effect of prior exposure with the original COVID-19 strain.
