Positive Phase 1 Results for the Novavax COVID-19 Vaccine

September 11, 2020
Jonna Lorenz

Results of the trial of Novavax’s NVX-CoV2373 vaccine have been published in the New England Journal of Medicine, showing the vaccine appeared safe and elicited strong immune responses.

Development of Novavax’s adjuvanted, recombinant, full-length spike protein nanoparticle vaccine NVX-CoV2373 for coronavirus 2019 (COVID-19) is moving forward after positive results were published from its phase 1 trial.

The results were detailed in the New England Journal of Medicine, following an earlier announcement from the company, showing the vaccine appeared safe and elicited strong immune responses at day 35 of the randomized, observer-blinded, and placebo-controlled trial.

“The rapid publication of phase 1 results from our trial in a prestigious peer-reviewed journal reflects both the importance of the data and the urgent need for an effective vaccine to slow the COVID-19 pandemic,” Gregory M. Glenn, MD, president of research and development at Novavax, said in a statement. “Based on the positive phase 1 results, we have begun multiple phase 2 clinical trials, from which we expect to collect preliminary efficacy. Novavax is committed to generating the safety, immunogenicity and efficacy data that will support confident usage of the vaccine, both in the US and globally.”

Phase 2 trials expand the age range to include participants ages 60-84 in the United States and Australia.

The first phase of the trial involved 131 participants ages 18-59 at 2 sites in Australia, evaluating the vaccine in 5-μg and 25-μg doses with or without the company’s proprietary Matrix-M1 adjuvant. Participants were divided into 5 groups, with 83 receiving the vaccine with adjuvant, 25 without adjuvant and 23 receiving a placebo. They received 2 doses given 21 days apart.

No serious adverse events were reported. One person reported a mild fever that lasted 1 day, and 4 reported headache, fatigue, malaise or tenderness.

All participants in the 5 µg group developed anti-spike IgG antibodies after a single dose. All participants developed wild-type virus neutralizing antibody responses after the second dose. Peak geometric mean titer (GMT) greater than 1:3,300 was generated by adjuvanted doses at both dosing levels.

Including the adjuvant with the 5 µg dose showed similar immune responses to the higher dose and induced a T cell response. The 2-dose adjuvanted regimen resulted in anti-spike IgG and viral neutralization responses that exceeded those of human convalescent serum from patients with clinically significant COVID‑19 disease.

Limitations include the small size of the trial, short follow-up period, lack of diversity, and young age and good health of the participants.

“The primary safety and immunogenicity analyses indicate that in healthy adult participants 18 to 59 years of age, two-dose regimens of 5 μg and 25 μg of rSARS-CoV-2 plus the Matrix-M1 adjuvant had acceptable safety findings and induced high immune responses, with levels of neutralizing antibodies that closely correlated with anti-spike IgG,” the study noted. “Furthermore, neutralizing antibody responses after the second vaccination with rSARS-CoV-2 plus Matrix-M1 exceeded values seen in symptomatic Covid-19 outpatients and were of the magnitude seen in convalescent serum from hospitalized patients with Covid-19.”

Novavax joined 8 other biotechnology companies in announcing a pledge to uphold the integrity of the scientific process as they work toward approvals of the first COVID-19 vaccines.

The company reached an agreement in principle with the Canadian government to provide 76 million doses of the vaccine to the Canada, the company announced late last month.

Follow updates about active vaccine candidates that are being studied for COVID-19 in the Contagion® COVID-19 Live Vaccine Tracker.