The Novavax COVID-19 vaccine uses a different strategy for immunization against SARS-CoV-2 than the mRNA vaccines from Pfizer and Moderna. Novavax utilizes a protein-based technology, a more traditional approach used for decades to protect against diseases like hepatitis and shingles. This formulation provides a non-mRNA alternative for preventing COVID-19.
A Different Approach to Vaccination
The Novavax vaccine is a protein subunit vaccine, meaning it directly introduces the virus’s spike protein to the immune system. To create these proteins, scientists use an engineered virus to transfer genetic instructions for the spike protein into moth cells. These moth cells then act as miniature factories, producing large quantities of the spike protein.
Once produced, these spike proteins are harvested, purified, and assembled onto synthetic nanoparticles that mimic the coronavirus’s structure. These particles contain no genetic material, making them incapable of causing infection. This premade spike protein is the final product, offering a “shortcut” compared to mRNA vaccines, which instruct the body’s cells to manufacture the protein.
The Novavax vaccine contains the Matrix-M adjuvant, an ingredient that helps create a stronger immune response. Matrix-M is derived from saponins extracted from the bark of the soapbark tree. This substance encourages immune cells to activate, boosting the body’s production of protective antibodies.
Effectiveness Against COVID-19
Clinical trials demonstrated the Novavax vaccine’s effectiveness in preventing COVID-19. Initial Phase 3 trials showed high efficacy against the original SARS-CoV-2 strain. A trial in the United Kingdom found the vaccine to be 96.4% effective against mild, moderate, and severe disease, with 100% protection against severe outcomes like hospitalization and death.
The vaccine also showed effectiveness against various strains. In early trials, efficacy against the Alpha variant was 86.3%. Later studies in adolescents, conducted when the Delta variant was predominant, showed an overall efficacy of nearly 80%.
Updated versions of the Novavax vaccine have been developed to target newer variants. A JN.1 version became available for 2024-2025. The authorization for these updated formulas was based on data showing they produce broad cross-neutralizing antibodies against multiple variant strains, providing protection against emerging Omicron variants.
Known Side Effects
The most frequently reported side effects for the Novavax vaccine are mild to moderate and temporary. These reactions are signs that the immune system is building protection and include:
- Pain, tenderness, or swelling at the injection site
- Fatigue
- Headache
- Muscle or joint pain
- Nausea or vomiting
More serious side effects are rare. Regulatory agencies identified a potential risk of myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the lining around the heart). These conditions have been observed in a small number of cases, often within a week of vaccination and more frequently in adolescent and young adult males.
While these events are uncommon, it is important to note that COVID-19 infection itself carries a higher risk of causing myocarditis or pericarditis than the vaccine. Individuals are advised to seek immediate medical attention if they experience symptoms like chest pain, shortness of breath, or palpitations after vaccination.
Current Recommendations and Availability
The Novavax vaccine is an authorized option in the United States for specific populations. In May 2025, the FDA approved the vaccine for individuals aged 65 and older. It is also approved for people aged 12 to 64 with at least one health condition that puts them at higher risk for severe COVID-19, making it the only non-mRNA vaccine with full FDA approval for these groups.
The Centers for Disease Control and Prevention (CDC) recommends the updated 2024-2025 Novavax formula for those aged 12 and older. A single dose is recommended for most people in this age group. However, a two-dose primary series is advised for adults 65 and older receiving it for the first time.
The vaccine’s availability provides a non-mRNA alternative for those unable or unwilling to receive mRNA vaccines. Because recommendations can evolve, consult official sources like the CDC for the most current guidance on vaccination schedules and eligibility.