About 1 billion people worldwide get the flu each year. Flu shots reduce hospitalizations and deaths, but they are less effective when the vaccine strains don’t closely match the viruses circulating in the community. A broader immune response could translate to a more effective vaccine even when the virus is changing faster than vaccine makers can update their shots.

The vaccine, developed by Moderna, is currently under review by the U.S. Food and Drug Administration, and if approved, would be the first against influenza using mRNA technology.

The findings are published in Nature Immunology.

“We are seeing that the mRNA flu vaccine doesn’t just boost the immune system’s response to what it has already seen, it can help expand and diversify the antibody response, covering a broader range of flu strains,” said Ali Ellebedy, Ph.D., the Leo Loeb Professor in the WashU Medicine Department of Pathology & Immunology and the study’s senior author.