Novavax Vaccine Shows 90.4% Efficacy Against COVID-19

Novavax’s COVID-19 vaccine was safe and effective in adults in the United States and Mexico, according to the latest phase 3 trial, which showed efficacy of 90.4%.

The study, published in the New England Journal of Medicine, included 29,949 participants who enrolled in the study between Dec. 27, 2020, and Feb. 18, 2021, with 19,714 receiving the vaccine and 9868 receiving a placebo. The trial was called the Prefusion Protein Subunit Vaccine Efficacy Novavax Trial–COVID-19 (PREVENT-19).

“PREVENT-19 showed that NVX-CoV2373, a recombinant protein nanoparticle vaccine, demonstrated an overall efficacy of 90.4%, which was achieved while variants were circulating in the US,” Lisa Dunkle, MD, vice president and global medical lead at Novavax, told Contagion. “Further, among the 77 cases, (14 among vaccine recipients and 63 among placebo recipients), all moderate and severe cases occurred in the placebo group. The side effect profile was acceptable, with reactogenicity mostly mild to moderate and transient.”

The median age of participants was 47 years, 49.2% were female, 75.9% were White, 11.0% were Black or African American, 6.2% were Native American or Alaska Native and 21.5% were Hispanic or Latino. About 47% of participants reported one or more coexisting conditions.

“The trial enrolled relatively quickly, so we were pleased with the level of interest and the level of demographic diversity among participants,” Dunkle said. “Vaccines began to become available under emergency use authorization at the beginning of the trial, which caused us to pivot in terms of our demographic enrollment goals.”

The study results are consistent with previous trials in the United Kingdom and South Africa that demonstrated clinical efficacy of the vaccine. The company announced in November it had applied for authorization from Health Canada and the European Medicines Agency. The vaccine has received emergency use authorization in Europe, Indonesia and the Philippeans and is currently under review in several other areas.

The predominant variants detected in the United States and Mexico during the study period were Alpha, Beta, Gamma, Epsilon and Iota.

Participants were followed through April 19, with 77 confirmed COVID-19 cases reported, including 14 in the vaccine group and 63 in the placebo group, yielding vaccine efficacy of 90.4% (95% CI, 82.9 to 94.6; P<0.001). Vaccine efficacy against moderate to severe disease was 100% (95% CI, 87.0 to 100), with all 10 moderate cases and 4 severe cases reported among participants in the placebo group and none in the vaccine group.

“Our clinical trial data show that the immune response generated by NVX-CoV2373, including the production of neutralizing antibodies, produced a high level of protection against COVID-19 illness,” Dunkle said. “In addition, more recent in vitro data show that the immune response to NVX-CoV2373 is cross reactive to all variants tested. That is encouraging for how the vaccine might perform amid Omicron and variants that could emerge in the future.”

The most commonly reported adverse events were pain and tenderness at the injection site for two days or less. Other adverse events included headache, myalgia, fatigue and malaise, typically lasting less than a day. Fever was reported in less than 1% of participants and was similar in both groups. The vaccine wasn’t associated with any adverse events that would trigger a pause in the study.

Novavax submitted its data to Food and Drug Administration for its emergency use authorization (EUA) application for its vaccine last week.

“NVX-CoV2373 is a new adjuvanted recombinant protein vaccine that can be added to the portfolio of vaccines that are safe and highly protective against contemporary SARS-CoV-2 strains and that have an acceptable side-effect profile,” Dunkle said. “The research was important because protein vaccines have been used widely for many years; we believe that this vaccine could make a difference in the future management of the pandemic.”