The Novavax COVID-19 vaccine is an alternative immunization against the SARS-CoV-2 virus. This vaccine utilizes a protein-based technology, a method used in vaccine development for decades. It functions by directly introducing a modified component of the virus to the immune system, prompting a protective response.
How Novavax Works
The Novavax vaccine, a protein subunit vaccine, operates by directly presenting the immune system with a modified version of the SARS-CoV-2 spike protein. Unlike other vaccine types, it does not instruct human cells to produce this protein. Instead, spike proteins are manufactured outside the human body using insect cells, specifically moth cells. These cells are infected with a baculovirus carrying the genetic code for the spike protein, acting as production factories.
After production, these lab-made spike proteins are harvested, purified, and assembled into tiny nanoparticles. The vaccine also incorporates an adjuvant called Matrix-M, derived from the bark of the Quillaja saponaria (soapbark) tree. Matrix-M enhances the immune response by activating innate immune cells at the injection site and in the draining lymph nodes, leading to a stronger antibody and T-cell response. This allows for a smaller dose of spike protein while still achieving a robust immune reaction.
Efficacy and Safety Profile
Clinical trials have shown Novavax to be effective in preventing COVID-19. In Phase 3 trials, the vaccine demonstrated an efficacy of 90.4% against symptomatic COVID-19 disease and 100% effectiveness in preventing moderate to severe disease requiring hospitalization. Efficacy was observed against variants circulating at the time, including the Alpha variant at 86.3% and non-Alpha strains at 96.4%.
Common side effects reported after Novavax vaccination are generally mild to moderate and typically resolve within a few days. These include pain, tenderness, and redness at the injection site, as well as fatigue, headache, muscle pain, joint pain, nausea, vomiting, and chills.
Rare but serious adverse events have been identified, including myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the lining outside the heart). These conditions typically manifest within 10 days of vaccination and have been observed more frequently in younger males aged 12-39 years. Serious allergic reactions like anaphylaxis are possible, usually occurring within minutes to an hour after vaccination.
Key Differences from mRNA Vaccines
The Novavax vaccine uses protein-based technology, unlike messenger RNA (mRNA) vaccines. Novavax directly introduces lab-made spike proteins, which are the viral components the immune system learns to recognize. These proteins are produced externally and then purified. In contrast, mRNA vaccines deliver genetic instructions to human cells, prompting them to temporarily produce the spike protein internally. The body’s immune system then recognizes these internally generated proteins and mounts a protective response.
Novavax also includes an adjuvant, Matrix-M, which actively boosts the immune response, a feature not typically present in mRNA vaccines. The Novavax vaccine can be stored at standard refrigerator temperatures, between 2°C and 8°C (36°F and 46°F), simplifying its distribution and storage. This traditional approach may appeal to individuals who prefer established technologies or have concerns about mRNA vaccines.
Eligibility and Availability
The Novavax COVID-19 vaccine has received regulatory authorization for use in various populations. It was initially authorized for individuals aged 18 and older, later expanding to include those 12 and older. As of May 2025, the FDA granted full approval for Novavax for people 65 years and older, and for individuals aged 12 to 64 with at least one underlying health condition increasing their risk for severe COVID-19 outcomes.
The current 2024-2025 formulation targets the JN.1 variant of SARS-CoV-2. It is available for primary vaccination and can also serve as a booster dose for adults at least six months after their primary series, particularly for those unable or unwilling to receive mRNA boosters. Novavax is accessible in various healthcare settings, including pharmacies and clinics, and is offered as a pre-filled syringe for ease of administration.