On May 20, 2022, Novavax announced the submission of a request to the European Medicines Agency (EMA) to expand the conditional marketing authorization (CMA) of Nuvaxovid (NVX-CoV2373) COVID-19 vaccine in the European Union (EU) as a homologous and heterologous booster dose for individuals aged 18 and over.

This request for expanded CMA was supported by data from Novavax’ Phase 2 trial conducted in Australia, from a separate Phase 2 trial conducted in South Africa, and from the UK-sponsored COV-BOOST trial. As part of the Phase 2 trials, a single booster dose of Nuvaxovid was administered to healthy adult participants approximately six months after their primary two-dose vaccination series of NVX-CoV2373. The third dose produced increased immune responses comparable to or exceeding levels associated with protection in Phase 3 clinical trials. In the COV-BOOST trial, NVX-CoV2373 induced a robust antibody response when used as a heterologous third booster dose.

Following the booster, local and systemic reactions were generally short-lived with a median duration of approximately two days. The incidence of Grade 3 or higher events remained relatively low. Safety reporting of reactogenicity events showed an increasing incidence across all three doses of NVX-CoV2373, reflecting the increased immunogenicity seen with a third dose. Medically attended adverse events, potentially immune-mediated medical conditions, and severe adverse events occurred infrequently following the booster dose and were balanced between vaccine and placebo groups.