Experts analyse Novavax COVID-19 vaccine efficacy data

Biotech News: Novavax announced NVX-CoV2373, its protein-based COVID-19 vaccine candidate, met the primary endpoint, with a vaccine efficacy of 89.3%, in its Phase 3 clinical trial conducted in the United Kingdom (UK).

The study assessed efficacy during a period with high transmission and with a new UK variant strain of the virus emerging and circulating widely. It was conducted in partnership with the UK Government’s Vaccines Taskforce. Novavax also announced successful results of its Phase 2b study conducted in South Africa.

“With today’s results from our UK Phase 3 and South Africa Phase 2b clinical trials, we have now reported data on our COVID-19 vaccine from Phase 1, 2 and 3 trials involving over 20,000 participants. In addition, our PREVENT-19 US and Mexico clinical trial has randomized over 16,000 participants toward our enrollment goal of 30,000. NVX-CoV2373 is the first vaccine to demonstrate not only high clinical efficacy against COVID-19 but also significant clinical efficacy against both the rapidly emerging UK and South Africa variants,” said Stanley C. Erck, President and Chief Executive
Officer, Novavax. “NVX-CoV2373 has the potential to play an important role in solving this global public health crisis. We look forward to continuing to
work with our partners, collaborators, investigators and regulators around the world to make the vaccine available as quickly as possible.”

Dr Roger Lord, senior lecturer at the Faculty of Health Sciences at The Australian Catholic University and Research Fellow at The Prince Charles Hospital in Brisbane, said “The media release of phase 3 (UK) and 2b (South Africa) clinical trial results for the Novavax COVID-19 vaccine are encouraging but must be considered carefully. These results have not been subject to a peer review process and the reported vaccine efficacy of 89.3% (UK trial) only an estimate. Interim analysis was based on only 62 individuals however it is promising that COVID-19 transmission was significantly lower in those who received the vaccine compared with those that received only a placebo.

“The emergence of the more virulent strains of COVID-19 during the UK clinical trial has been fortuitous for Novavax, providing evidence that the vaccine has efficacy against COVID-19 and UK and South African variants. This does not mean however that COVID-19 vaccines from Pfizer, Moderna or Oxford-AstraZeneca are less effective, only that currently clinical data is lacking to confirm efficacy against the variants.

“Interim analysis provided in the media release for safety of the Novavax vaccine is rather ambiguous and reads “.. showed that severe, serious and medically attended adverse events occurred at low levels and were balanced between vaccine and placebo groups”. I am uncertain what Novavax considers a low level, exactly how many events were serious, and clarification required as to what is considered a balance between cohorts.”

Professor Raina MacIntyre, Head of the Biosecurity Program at the Kirby Institute at the University of NSW and an expert in influenza and emerging infectious diseases, said “The news from Novavax is mixed. This is the first efficacy data we have seen from a protein-based vaccine. This is also the first evidence that clinical efficacy is reduced against the variants of concern that have arisen in the UK and South Africa. In the UK, it was 95% against the original SARS CoV 2 and 85% against the B117 UK variant. Overall this was 89%.

“More worryingly, in South Africa, where the B1351 variant was dominant, it was only 60% effective, and as low as 49% when HIV infected people were included in the analysis. B1351 in South Africa and P1 in Brazil have two additional sites of mutation compared to the UK B117, so may be more resistant to vaccines, now confirmed by the Novavax data.

“This means we urgently need to know the efficacy of other vaccines in the Australian plan, such as Astra Zeneca and Pfizer, against these variants, and plan accordingly. They all target the same protein, so we can expect reduced efficacy to variant strains with these vaccines. These are likely to become the dominant strains globally and are more contagious, and the B117 appears to be more severe.

“In Manaus, Brazil, the P1 variant, which has mutations in the same three regions as the South African variant, seems to be infecting people who were already infected in 2020, so it’s like a new pandemic. Meanwhile, our border control measures are more important than ever to mitigate the risk of variant strains causing an epidemic here.

“Additionally, the data also tell us that we need high efficacy vaccines for immunosuppressed people, as they do not respond as well,” she added

The Coalition for Epidemic Preparedness Innovations (CEPI) funded the manufacturing of doses of NVX-CoV2373 for this Phase 2b clinical trial,
which was supported in part by a $15 million grant from the Bill & Melinda Gates Foundation.