TUESDAY, Feb. 17, 2015 (HealthDay News) — Seasonal flu vaccines trigger immune system protection against the deadly H7N9 bird flu virus, a new study reveals.

This strain of bird flu, which emerged in China in 2013, kills nearly one-third of people infected with it, the researchers noted.

“We have clear evidence that a normal immune response to flu vaccination offers protection against dangerous and highly unique strains of influenza such as H7N9,” study co-senior author Patrick Wilson, an associate professor of medicine at the University of Chicago, said in a university news release.

“We now need to develop ways of amplifying this response,” he added.

The researchers tested 83 immune system antibodies from 28 people who received a seasonal flu vaccine. Of those antibodies, 7 percent reacted against rare H7 virus strains, even though those strains were not specifically targeted by the seasonal flu vaccines.

Three of the antibodies appeared to completely neutralize the H7N9 bird flu virus, and these findings were confirmed in tests in mice, according to the study published Feb. 17 in the Journal of Clinical Investigation.

“It appears more common than previously thought for antibodies induced by flu vaccination to offer cross-protection against H7N9,” study author Carole Henry, a postdoctoral fellow at the University of Chicago, said in the news release.

“Although they are not always protective, H7-reactive antibodies can be found in almost everyone that’s been vaccinated,” she added.

The challenge, Wilson said, is “to exploit this response on a larger scale to make vaccines or therapeutics that offer broad protection against influenza strains.”

For now, he added, it’s clear that seasonal flu vaccination provides protection against more than just common strains. “Everyone should be vaccinated,” he said.

— Robert Preidt

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SOURCE: University of Chicago, news release, Feb. 17, 2015