Novavax COVID-19 Vaccine Elicits Wild-Type Virus Neutralizing Antibody Responses in 100% of Participants in Phase 1/2 Trial

Novavax, Inc. (Gaithersburg, MD, USA) has announced positive Phase 1 data from its Phase 1/2 randomized, observer-blinded, placebo-controlled trial of its COVID‑19 vaccine with and without Matrix‑M adjuvant in healthy adults 18-59 years of age.

NVX‑CoV2373, the company’s recombinant COVID-19 vaccine candidate adjuvanted with Matrix-M, was generally well-tolerated and elicited robust antibody responses numerically superior to that seen in human convalescent sera. Overall, the vaccine was well-tolerated and reactogenicity events were generally mild. Following Dose 1, tenderness and pain were the most frequent local symptoms and systemic events were individually less frequent with headache, fatigue and myalgia being reported most commonly. As expected, following Dose 2, greater reactogenicity was reported, although the majority of symptoms were reported as ≤ Grade 1. The average duration of events was < 2 days. Unsolicited adverse events were collected through 28 days after Dose 2. There were no severe (Grade 3) unsolicited adverse events, and the vast majority of adverse events were mild and deemed not related to vaccination. No serious adverse events (SAEs) were reported and safety follow-up continues.


All subjects developed anti-spike IgG antibodies after a single dose of vaccine, many of them also developing wild-type virus neutralizing antibody responses, and after Dose 2, 100% of participants developed wild-type virus neutralizing antibody responses. Both anti-spike IgG and viral neutralization responses compared favorably to responses from patients with clinically significant COVID‑19 disease. Importantly, the IgG antibody response was highly correlated with neutralization titers, demonstrating that a significant proportion of antibodies were functional. The adjuvant was dose-sparing, with the lower 5 µg dose of NVX‑CoV2373 performing comparably with the 25 µg dose. Cellular immune responses were measured in a subset of participants, and NVX‑CoV2373 induced antigen-specific polyfunctional CD4+ T cell responses with a strong bias toward the Th1 phenotype (IFN-g, IL-2, and TNF-a). NVX-CoV2373 is stable and will allow handling in a liquid formulation that can be stored at 2°C to 8°C, allowing for successful cold chain management with existing infrastructure.

“The Phase 1 data demonstrate that NVX-CoV2373 with our Matrix-M adjuvant is a well‑tolerated COVID-19 vaccine with a robust immunogenicity profile,” said Gregory M. Glenn, M.D., President, Research and Development at Novavax. “Using a stringent wild-type virus assay performed by investigators at the University of Maryland School of Medicine, NVX‑CoV2373 elicited neutralizing antibody titers greater than those observed in a pool of COVID‑19 patients with clinically significant disease.”

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