The FDA has granted emergency use authorization (EUA) for the Novavax COVID-19 vaccine, adjuvanted, as a first booster dose at least 6 months after primary vaccination with an authorised COVID-19 vaccine in adults 18 years of age and older who are unable to receive an mRNA bivalent COVID-19 booster vaccine.

Data from the phase 3 PREVENT-19 trial and the UK-sponsored COV-BOOST trial were used to make the decision. In the PREVENT-19 trial, healthy adult participants aged 18 and older received a single booster dose of the vaccine approximately 8 or 11 months after their primary series. Following this dose, antibody levels rose significantly in comparison to pre-booster levels, exceeding levels associated with protection in the phase 3 trial. When administered 8 or 11 months after the primary series, neutralising antibodies increased 34 to 27-fold compared to pre-booster levels.

The Novavax COVID-19 vaccine adjuvanted increased antibody titers in the COV-BOOST trial when used as a third dose following initial dosing with another authorised COVID-19 vaccine. Local and systemic reactions had a median duration of about 2 days after the booster.

The occurrence of grade 3 or higher adverse events remained low. Reactogenicity events, which are frequently associated with increased immunogenicity, were reported with increasing frequency across all three doses of the vaccine. Injection site pain or tenderness (81.1%), fatigue or malaise (63.4%), muscle pain (63%), headache (52.9%), joint pain (30.3%), nausea or vomiting (14.7%), injection site swelling (8.4%), injection site swelling (8.4%), injection site swelling (8.4%), injection site swelling (8.4%), injection site swelling (8.4%), injection site swelling (8.4%), injection site swelling (8.4%), injection site swelling (8.4%), injection site swelling (8.4%), injection site swelling (8.4%), injection site infection, fever.

Almost half of adults who received their primary series have yet to receive their first booster dose, according to CDC data. The Novavax COVID-19 vaccine provides another option that may help increase COVID-19 booster vaccination rates among adults in the United States.

The vaccine's next step is a CDC policy recommendation for its use as a first booster. Doses are currently available for the United States pending the completion of this final step.

Several countries have already issued policy recommendations that allow the vaccine to be used as a heterologous or homologous booster dose. In the United States, the FDA granted an EUA in July 2022 for a 2-dose primary series with the Novavax COVID-19 vaccine in adults aged 18 and older, and in August for adolescents aged 12 to 17 years. The vaccine was also recommended by the CDC for use as a primary series in both age groups.