THE NEW FORMULATION — The 2024-2025 formulation of the Novavax vaccine contains the spike protein of the JN.1 Omicron strain of SARS-CoV- 2. Currently prevalent "FLiRT" variants (e.g., KP.2, KP.2.3, KP.3, KP.3.1.1, LB.1) are descended from the JN.1 strain.4,5 The Pfizer and Moderna 2024-2025 vaccines code for the spike protein of the KP.2 strain.3

EFFECTIVENESS — As with the mRNA COVID-19 2024-2025 vaccines, no clinical studies evaluating the immunogenicity or effectiveness of the 2024- 2025 Novavax vaccine are available. Authorization of the new formulation was based on the immunogenicity, safety, and efficacy of previous vaccine formulations.1,2

Observational studies suggest that all of the 2023-2024 formulations of the COVID-19 vaccines available in the US were effective in reducing the incidence of COVID-19, but data specific to the Novavax vaccine are limited. In a case-control analysis of 14,860 COVID-19 nucleic acid amplification tests administered at community pharmacies to immunocompetent adults with COVID-like symptoms between September 2023 and May 2024, receipt of any 2023-2024 COVID-19 vaccine at least 7 days before the test was associated with a decreased incidence of SARS-CoV-2 infection. The estimated adjusted vaccine efficacy was 45%; it was 58% for infections likely caused by the XBB.1.5 variant, which the 2023-2024 vaccines targeted, and 37% for infections likely caused by the JN.1 variant.6,7

In similar analyses of tests administered to adults with COVID-like illness within 10 days before or 3 days after an emergency department/urgent care visit (n=245,504) or a hospitalization (n=77,103) between September 2023 and May 2024, receipt of any 2023-2024 COVID-19 vaccine at least 7 days before the test was associated with a decreased incidence of COVID-19 requiring an emergency department/urgent care visit (estimated adjusted vaccine efficacy 36%) or hospitalization (estimated adjusted vaccine efficacy 42%). Among hospitalized immunocompetent persons, the estimated adjusted vaccine efficacy against critical illness was 58%.6,8

ADVERSE EFFECTS — Adverse effects of previous formulations of the Novavax vaccine have included injection-site pain/tenderness, fatigue/malaise, myalgia, arthralgia, headache, nausea, and vomiting. Hypersensitivity reactions, myocarditis, and pericarditis have occurred rarely; the incidence of myocarditis and pericarditis is highest in adolescent and young adult males.9

DOSAGE RECOMMENDATIONS — The 2024-2025 Novavax COVID-19 vaccine is indicated for use in persons ≥12 years old. Generally, persons who have not been vaccinated against COVID-19 previously should receive 2 doses 3-8 weeks apart. Those who have been vaccinated against COVID-19 previously should receive a single 0.5-mL dose ≥2 months after their last COVID-19 vaccine dose. Additional doses, each given ≥8 weeks after the previous dose, can be considered for persons with immunocompromise (solid-organ transplant recipients and equivalent).2,10

CDC RECOMMENDATIONS — The CDC recommends that all persons ≥6 months old be immunized with a 2024-2025 COVID-19 vaccine formulation. Persons ≥12 years old can receive a Pfizer, Moderna, or Novavax vaccine. Persons 6 months to 11 years old should receive a Pfizer or Moderna vaccine.10

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