The PREVENT-19 pivotal Phase 3 trial reported 80% efficacy for the Novavax vaccine in children. According to the company, its COVID-19 vaccine NVX-CoV2373 achieved its primary effectiveness endpoint in the pediatric expansion of the study at a time when the Delta variant was the predominant circulating strain in the US.
The study enrolled 2,247 adolescents aged 12 through 17-years across 73 sites in the US to evaluate safety, effectiveness (immunogenicity), and efficacy, with an emphasis on ensuring well balanced racial and ethnic representation among participants.
NVX-CoV2373 has not yet been authorized in the adolescent population. Novavax expects to submit its regulatory filings for a pediatric indication in adolescents aged 12 through 17-years to global regulatory authorities during the first quarter of 2022. Novavax also expects to initiate additional studies globally evaluating younger age groups during the second quarter of 2022.
In the placebo-controlled, observer-blinded study, adolescent participants were randomized 2:1 to receive active vaccine or placebo. Study participants underwent blinded crossover to alternate study material after the required safety data were collected to ensure that all participants received active vaccine. During the period of placebo-controlled observation, NVX-CoV2373 demonstrated overall protective efficacy of 79.5% (95% CI: 46.8, 92.1) against COVID-19. Efficacy was consistent across age groups and all cases observed in the vaccine group were mild as defined by the trial protocol.
Efficacy endpoints were accrued from May 24 through September 27, 2021 – a time when the Delta variant was the predominant strain in the U.S., showing high transmission and high severity of disease. Sequence data are available for 11 of the 20 confirmed cases, 100% of which were determined to be caused by the Delta variant. Vaccine efficacy against the Delta variant was 82.0% (95% CI: 32.4, 95.2).
“We are encouraged by the results in this adolescent population given the ongoing need for alternative vaccine options for COVID-19,” said Filip Dubovsky, MD, Chief Medical Officer, Novavax. “We believe the Novavax vaccine offers a differentiated technology and option for this younger population given its established protein-based technology already used in other vaccines, and the positive responses demonstrated against variants.”
The primary PREVENT-19 pivotal Phase 3 trial conducted in adults aged 18 years and older, results of which were published in The New England Journal of Medicine (NEJM), enrolled approximately 30,000 participants in the U.S. and Mexico. NVX-CoV2373 achieved 90.4% efficacy overall and demonstrated a reassuring safety and tolerability profile. Serious and severe adverse events in adults were low in number and balanced between vaccine and placebo groups. The most common adverse reactions observed in adults during clinical studies (frequency category of very common ≥1/10) were headache, nausea or vomiting, myalgia, arthralgia, injection site tenderness/pain, fatigue, and malaise. Novavax will continue to collect and analyze real-world data, for both the primary PREVENT-19 trial and the pediatric expansion, including the monitoring of safety and the evaluation of variants, as the vaccine is distributed.