Results of UK phase 3 clinical trial for Novavax Covid-19 vaccine published

Published: 02 July 2021

Novavax have announced the publication of results from the final analysis of its Phase 3 clinical trial of its Covid-19 vaccine (NVX-CoV2373), conducted in the UK and led by researchers at the Vaccine Institute at St George’s.

Published in the New England Journal of Medicine (NEJM), the final analysis confirmed an overall efficacy of 89.7% with over 60% (half) of the cases caused by the B.1.1.7 (Alpha) variant of Covid-19, and a 96.4% efficacy against non-B.1.1.7 (non-Alpha) variants which represents strains most similar to the original virus.

The published results provide the final trial analysis, building on an initial interim analysis conducted in January 2021, and the updated analysis announced in March 2021.

"We continue to be very encouraged by data showing high levels of efficacy against even mild disease, and that NVX-CoV2373 offers strong cross-protection against both the B.1.1.7 (Alpha) variant and non-B.1.1.7 (non-Alpha) variant strains which are widely circulating," said Gregory M. Glenn, M.D., President of Research and Development at Novavax.

"This publication also reinforces the reassuring safety and efficacy profile shown in studies of our vaccine to date and underscores the potential for NVX-CoV2373 to play an important role in solving this ongoing global public health crisis."

The randomised, observer-blinded, placebo-controlled study, led by researchers at St George's, University of London and St George's Hospital and supported by the National Institute for Health Research (NIHR), enrolled more than 15,000 adults at trial sites across the United Kingdom.

The research demonstrated that two doses of Novavax's Covid-19 vaccine candidate resulted in 96.4% protection against non-B.1.1.7 (non-Alpha) variant strains and nearly 90% protection against all strains in circulation at that time. It also demonstrated that initial vaccine side effects were mostly mild and transient, and that the incidence of serious adverse events was low and similar between those receiving the vaccine and those receiving a placebo. The study assessed efficacy during a period when the B.1.1.7 (Alpha) variant strain of the virus was emerging and circulating widely in the United Kingdom and is the same variant that is currently widespread in the United States.

"It is quite remarkable how well the vaccine efficacy from our United Kingdom trial matches the results seen in the United States in the recently released PREVENT-19 trial results, giving even more confidence in the potential role of this vaccine in helping to control the pandemic," said Professor Paul Heath, Director of the Vaccine Institute at St George's, University of London and St George's Hospital and chief investigator of the Novavax UK trial.

"It really highlights the consistent performance of this vaccine in different populations and against a variety of evolving strains," he added.

The vaccine is still awaiting regulatory approval in the UK.