Preclinical Data Shows Potential for Bird Flu Candidate

Novavax’s H5N1 avian influenza vaccine candidate shows a robust immune response with 1- and 2-dose intranasal or intramuscular administration for nonhuman primates.

"These preclinical results underscore the promise and potential of our pandemic influenza program as well as the strength of our technology platform and our ability to deliver against our corporate growth strategy," Ruxandra Draghia-Akli, MD, PhD, executive vice president and head of research and development at Novavax, said in a news release. "Our R&D pipeline focuses on delivering assets ready for partnership and prioritizing areas of unmet medical need, including vaccines for avian pandemic influenza, where we see clear potential advantages for our technology compared with other vaccines that are licensed or in development."

H5N1, also known as bird flu, is generally mild in North America, with only 70 human cases reported since May 2025. Although the transmission has halted as of July 7, 2025, authors in a review posted in The Lancet stated that there are several concerns with bird flu that have raised alarm. Human H5N1 infections primarily result from transmission from birds to humans, but employees working in dairy or poultry should take precautions for bird flu exposure.

In the current study, investigators found that a single dose of the vaccine in either route induced neutralizing antibody responses at or above the 1.40 titer, which is considered a protective antibody response. Further, there were higher levels of immunity after 2 doses, according to the study authors. Even as an intranasal dose, the vaccine has the potential to protect individuals previously exposed to seasonal influenza by vaccination or infection, including the potential to protect against currently circulating strains of the H5N1 virus.

“Our findings indicate that a single IM intramuscular dose of an A/AW/SC/2021 H5-MNP vaccine might serve as an effective pandemic vaccine in individuals with pre-existing seasonal influenza HA immunity from vaccination or infection,” the study authors wrote. “Two IN intranasal doses might be considered as an at-home self-administered booster in seasonal influenza-primed individuals during a pandemic, and a single IN H5-MNP vaccine dose could be valuable for pandemic preparedness.”