On May 3, 2021, Novavax announced that it had initiated a pediatric expansion of its Phase 3 clinical trial for NVX-CoV2373, the company’s recombinant protein vaccine candidate against COVID-19. The additional arm of the ongoing PREVENT-19 pivotal trial evaluated the efficacy, safety and immunogenicity of NVX-CoV2373 in up to 3,000 adolescents aged 12-17 across up to 75 sites in the U.S.

Participants randomly received either the vaccine candidate or placebo in two doses, administered 21 days apart. Two-thirds of volunteers received intramuscular injections of the vaccine and one-third received placebo. A blinded crossover was planned to take place six months after the initial set of vaccinations to ensure that all trial participants received active vaccine. Participants were monitored for safety for up to two years following the final dose.