Novavax, Inc. announced that it submitted an application to the U.S. Food and Drug Administration (FDA) for Emergency Use Authorization (EUA) of its protein-based COVID-19 Vaccine, Adjuvanted for active immunization to prevent coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as a homologous and heterologous booster in adults aged 18 and older. This application for EUA is supported by data from Novavax' Phase 3 PREVENT-19 trial conducted in the United States and Mexico, and from the UK-sponsored COV-BOOST Phase 2 trial. As part of an open-label booster phase of the PREVENT-19 trial, a single booster dose of the Novavax COVID-19 Vaccine, Adjuvanted was administered to healthy adult participants at least six months after their primary two-dose vaccination series of the Novavax COVID-19 Vaccine, Adjuvanted.

The third dose produced robust antibody responses comparable to or exceeding levels associated with the efficacy data in the primary series Phase 3 clinical trials. In the COV-BOOST trial, the Novavax COVID-19 Vaccine, Adjuvanted induced a significant antibody response when used as a heterologous third booster dose. In the PREVENT-19 trial, following the booster, local and systemic reactions had a median duration of approximately two days.

Safety reporting of reactogenicity events showed an increasing incidence across all three doses of the Novavax COVID-19 Vaccine, Adjuvanted, 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. In the U.S., the FDA granted EUA, followed by a positive recommendation from the U.S. Centers for Disease Control and Prevention's (CDC) Advisory Committee on Immunization Practices (ACIP), and endorsement from the CDC for a two-dose primary series in adults aged 18 and older in July. Doses of the Novavax COVID-19 Vaccine, Adjuvanted have been available for use in the U.S. since July.  This project has been supported in part with federal funds from the Department of Health and Human Services (HHS); the Administration for Strategic Preparedness and Response; Biomedical Advanced Research and Development Authority (BARDA), through the Department of Defense Joint Program Executive Office for Chemical, Biological, Radiological and Nuclear Defense (JPEO-CBRND) under contract number MCDC2011-001.