Dunkle LM, Kotloff KL, Gay CL, et al. - Researchers aimed at evaluating the efficacy and safety of NVX-CoV2373 for the prevention of coronavirus disease 2019 (Covid-19) in adults (≥ 18 years of age) in North America who had not had severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.

• During the first half of 2021, a phase 3, randomized, observer-blinded, placebo-controlled trial was conducted in the United States and Mexico.

• A total of 29,949 participants were randomized in a 2:1 ratio to receive two doses of NVX-CoV2373 or placebo 21 days apart.

• A total of 77 cases of Covid-19 were recorded over a period of 3 months — 14 among vaccine recipients and 63 among placebo recipients.

• Outcomes suggest that for the prevention of Covid-19, NVX-CoV2373 is safe and effective.

• Mostly contemporary variant strains were causative in breakthrough cases.