On Jun. 30, 2021, Novavax announced the publication of results from the final analysis of a pivotal Phase 3 clinical trial of its COVID-19 vaccine candidate conducted in the United Kingdom in the New England Journal of Medicine (NEJM). The final analysis confirmed an overall efficacy of 89.7% with over 60% (half) of the cases caused by the B.1.1.7 (Alpha) variant, and a 96.4% efficacy against non-B.1.1.7 (non-Alpha) variants which represented strains most similar to the original virus.

The randomized, observer-blinded, placebo-controlled study, led by researchers at St George’s, University of London and St George’s Hospital, London, enrolled more than 15,000 adults at trial sites across the United Kingdom. The research demonstrated that a two-dose regimen of Novavax’ COVID-19 vaccine candidate conferred 96.4% protection against non-B.1.1.7 (non-Alpha) variant strains and nearly 90% protection against all strains in circulation at that time. It also demonstrated that initial vaccine side effects were mostly mild and transient, and that no imbalance was seen in more serious adverse events compared with the placebo arm. The study assessed efficacy during a period when the B.1.1.7 (Alpha) variant strain of the virus was emerging and circulating widely in the United Kingdom and is the same variant that is currently widespread in the United States.

NVX-CoV2373 is a protein-based vaccine candidate engineered from the genetic sequence of the first strain of SARS-CoV-2, the virus that causes COVID-19 disease. NVX-CoV2373 was created using Novavax’ recombinant nanoparticle technology to generate antigen derived from the coronavirus spike (S) protein and is adjuvanted with Novavax’ patented saponin-based Matrix-M^TM to enhance the immune response and stimulate high levels of neutralizing antibodies. NVX-CoV2373 contains purified protein antigen and can neither replicate, nor can it cause COVID-19. In preclinical studies, NVX-CoV2373 induced antibodies that blocked the binding of spike protein to cellular receptors and provided protection from infection and disease. It was generally well-tolerated and elicited robust antibody response in Phase 1/2 clinical testing.

NVX-CoV2373 is being evaluated in two pivotal Phase 3 trials: a trial in the U.K. that demonstrated efficacy of 96.4% against the original virus strain, 86.3% against the B.1.1.7 (Alpha) variant and 89.7% overall; and the PREVENT-19 trial in the U.S. and Mexico that demonstrated 100% protection against moderate and severe disease and 90.4% efficacy overall. It is also being tested in two ongoing Phase 2 studies that began in August 2020: A Phase 2b trial in South Africa that demonstrated 55% efficacy overall in HIV-negative participants and 48.6% efficacy against a newly emerging escape variant first described in South Africa, and a Phase 1/2 continuation in the U.S. and Australia.

NVX-CoV2373 is stored and stable at 2°- 8°C, allowing the use of existing vaccine supply chain channels for its distribution. It is packaged in a ready-to-use liquid formulation in 10-dose vials.