Recently published data suggests Novavax’s investigational COVID-19 vaccine, NVX-CoV2373, is 90 percent effective at preventing COVID-19 illness and 100 percent effective at preventing moderate-to-severe symptoms.

The PREVENT-19 study (NCT04611802) recruited nearly 30,000 adult volunteers at 113 clinical sites in the US and six sites in Mexico, approximately 20,000 participants received two doses of the COVID-19 vaccine spaced three weeks apart and 10,000 received placebo.

Over a period of three months, 77 cases of COVID-19 were report, 14 among vaccine recipients and 63 among placebo recipients, resulting in a vaccine efficacy of 90.4 percent. A total of 10 moderate and four severe COVID-19 cases, all in placebo recipients, suggesting the vaccine is 100 percent effective in preventing moderate-to-severe disease that required hospitalisation.

Of the 61 viral genomes that were sequenced, 79 percent were variants of concern or interest, primarily variant Alpha. Vaccine efficacy against any variant of concern or interest was calculated to be 92.6 percent, based on the limited population that were sequenced. The assessment did not include Delta or Omicron variants.

Most vaccine side effects were mild to moderate and transient. Fever was very rare. The most common side effects in the vaccine recipients included pain and tenderness at the injection site, headache, muscle aches and fatigue that lasted a day on average. None of the recipients developed serious reactions like heart inflammation (myocarditis) or blood clots.

Commented on the results published in the New England Journal of Medicine, Dr Karen Kotloff, Professor of Pediatrics at the University of Maryland School of Medicine’s (UMSOM) Center for Vaccine Development and Global Health, and Co-Chair of the trial protocol, stated: “Our study results indicate that this vaccine is highly efficacious and very safe. In addition, this vaccine has many attractive features. It is made from a small piece of protein, like many currently licensed vaccines in the US and has convenient refrigerator storage requirements, so it will be an important addition to the COVID-19 vaccine portfolio, in the US and in countries where supply is lacking.”

The trial was part of Operation Warp Speed, a multi-agency collaboration led by the US Department of Health and Human Services (HHS), which aims to accelerate the development, manufacturing and distribution of medical countermeasures for COVID-19. Novavax and the National Institute of Allergy and Infectious Disease (NIAID) also provided funding for the study.

NVX-CoV2373 is an adjuvanted, recombinant Spike protein nanoparticle vaccine that was shown to have clinical efficacy for the prevention of COVID-19 in Phase IIb–III trials in the UK and South Africa.