Published on in Vaccine Update for Healthcare Providers
Early studies of a vaccine containing 5 micrograms (ug) of a recombinant nanoparticle SARS-CoV-2 spike protein plus 50 ug of Matrix-M (a saponin-based adjuvant containing cholesterol and phospholipid) showed that a two-dose regimen administered 21 days apart caused a robust immune response in healthy adults. Recently, investigators reported the results of a large efficacy trial of the vaccine (NVX-CoV2373, Novavax) (Heath PT, Galiza EP, Baxterm DN, et al. Safety and efficacy of NVX-CoV2373 Covid-19 vaccine. N Engl J Med. 2021 Sep 23;385:(13):1172-1183).
A phase 3, randomized, controlled clinical trial was conducted at 33 sites in the United Kingdom during which time the alpha variant of SARS-CoV-2 was the prevalent, circulating strain. About 14,000 participants were divided in half and given either the two-dose vaccine 21 days apart or placebo. Among participants, 28% were 65 years of age or older and 45% had co-existing illnesses. COVID-19 infections (either mild, moderate, or severe) were reported in 10 participants in the vaccine group and 96 in the placebo group for a vaccine efficacy of 89.7%. Five cases of severe disease were reported; all were in the placebo group. Reactogenicity was generally mild and transient. Among participants who were 65 years of age or older, vaccine efficacy was 88.9%.
Investigators concluded, “A two-dose regimen of the NVX-CoV2373 vaccine administered to adult participants conferred 89.7% protection against SARS-CoV-2 infection and high efficacy against the B.1.1.7 [alpha] variant.”
Pending review by the FDA and CDC, the Novavax vaccine adds another potential weapon in the fight against this pandemic.
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