THURSDAY, Aug. 22, 2024 (HealthDay News) -- A universal flu vaccine that would protect against all influenza strains -- and that people might not need to take every year -- could be close at hand, researchers report.

An experimental vaccine candidate produced a strong immune response in lab mice, and it provided protection against severe infection after the critters were exposed to the virus, researchers reported Aug. 22 in the Journal of Virology.

The candidate flu vaccine combines eight proteins from five different types of influenza virus, in hopes of providing immune protection against any type of flu that might strike the United States, researchers said. However, more investigation needs to be done, since animal-based trials don't always pan out in humans.

Using data from previous studies, researchers concluded that these eight proteins together could provide a sustained and universal immune response against the flu, said lead researcher Naoko Uno, a virologist and postdoctoral fellow with the Cleveland Clinic.

“We’ve been able to whittle down this list, to say these are the best at spanning multiple seasons and eliciting a broadly reactive antibody response,” Uno said of the eight proteins. “It’s like creating a greatest hits album. We want to put only the best ones back in the vaccine.”

Researchers believe the vaccine also might be able to last longer than a single season, potentially ending the annual ritual of flu jabs.

“We want to make sure our vaccine can span multiple seasons, not just one, and protect against all the strains that affect humans,” Uno said in a journal news release.

Seasonal flu vaccines include proteins from three or four flu strains, which are chosen by looking at which strains are circulating on the other side of the world during their influenza season.

But it’s a guessing game, because the flu virus mutates so quickly. An unanticipated flu strain could burst into the United States without warning, or a chosen protein might produce an inadequate immune response because the virus has changed subtly but significantly.

To craft a potential universal flu vaccine, researchers downloaded thousands of genetic sequences of flu strains spanning multiple seasons.

They then analyzed those sequences to identify which proteins were common across all flu strains.

The resulting vaccine includes proteins from H1, H2, H3, H5 and H7 types of influenza virus, researchers said.

H1 and H3 commonly circulate among humans, while the other types occur in animals but have pandemic potential if they leap into humans, researchers said.

For example, the H5N1 bird flu has been spreading rapidly through poultry and livestock in the United States, raising concerns that the flu could jump into people.

Researchers hope to launch human clinical trials for the universal vaccine within one to three years, Uno said.

More information

The U.S. Centers for Disease Control and Prevention has more on the seasonal flu vaccine.

SOURCE: American Society of Microbiology, news release, Aug. 22, 2024