On May 10, 2021, Novavax announced data from a preclinical study of the company’s combination quadrivalent seasonal flu vaccine (NanoFluﾙ) and COVID-19 vaccine candidate (NVX-CoV2373). The NanoFlu/NVX-CoV2373 combination vaccine demonstrated positive immune responses to both influenza and SARS-CoV-2. A pre-print of the manuscript was available at bioRxiv.org.

The manuscript, titled ‘Combination Respiratory Vaccine Containing Recombinant SARS-CoV-2 Spike and Quadrivalent Seasonal Influenza Hemagglutinin Nanoparticles with Matrix-M™ Adjuvant,’ studied a combination vaccine comprising a quadrivalent nanoparticle influenza vaccine formulated together with a recombinant SARS-CoV-2 spike protein vaccine and Matrix-M™ adjuvant. The combination vaccine elicited robust responses to both influenza A and B and protected against the SARS-CoV-2 virus. Clinical studies of the combination vaccine were expected to begin by the end of the year.

The preclinical study found that the combination NanoFlu/NVX-CoV2373 (qNIV/CoV2373) vaccine induced functional influenza and COVID antibodies in ferrets. Hemagglutination inhibition (HAI) and ACE2 receptor-inhibiting titers were comparable between immunization with the combination vaccine and with its respective component vaccines. Antibody titers were elevated two weeks after a single dose and increased even further two weeks following a second immunization.

Hamsters that received the combination NanoFlu/NVX-CoV2373 vaccine had elevated levels of SARS-CoV-2 anti-S IgG two weeks after the first immunization, which increased significantly after a second dose, with levels comparable to animals that received the NVX-CoV2373 vaccine alone. Human ACE2 receptor inhibiting antibody levels responded similarly. The immune responses to influenza A and B strains elicited by NanoFlu/NVX-CoV2373 were comparable to immunization with NanoFlu alone. Further, the combination vaccine induced antibodies against SARS-CoV-2 neutralizing epitopes, including at hidden or cryptic sites, that are common between USA-WA1 and the B.1.351 variant.

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™ 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.