SLU: Include both strains of influenza B in shot

Flu vaccines would probably protect children better if they included both strains of influenza B instead of just one, Saint Louis University (SLU) researchers say.

"Each year, the FDA selects two different subtypes of influenza A and one of the two B virus strains to put into the vaccine," says Robert Belshe, lead investigator and director of the Center for Vaccine Development at SLU, as reported by KMOX. "And only fifty percent of the time have they been right about which B virus to use. You might as well flip a coin to choose which vaccine type to put in there." So Belshe and his research team tested a theory on ferrets.

The team examined how well current vaccines protect against influenza B by looking at the immune response of ferrets that were given FluMist, a live attenuated influenza vaccine manufactured by MedImmune, and at efficacy studies in children who received traditional flu shots or FluMist. When ferrets were vaccinated against influenza, the ferrets that were exposed to a strain of influenza B virus that did not match what was in the vaccine didn't have a strong antibody response. However they had a vigorous antibody response when given a vaccine that contained both strains of influenza B.

This showed that immunizing against one strain of influenza B does not appear to protect against the other strain and that a vaccine containing both influenza B strains is likely to offer greater protection from flu. "These data highlight the need for vaccination strategies that provide enhanced protection against both lineages of influenza B," Belshe says in a statement.

Belshe says drug manufacturers are beginning to work on including both B viruses in their vaccine, but it is not yet available, KMOX reports.

- see the SLU press release
- check out the KMOX report