CDC reports flu vaccines this season not a good match for strains

WASHINGTON Every year, public health experts gather information to predict—eight months in advance—which strains of influenza are more likely to circulate in time to prepare mass quantities of the correct vaccine. They have been correct 16 of the last 19 years. Not this year, though, according to published reports.

Every flu vaccine contains a mixture of three of the main strains—two versions of type A and one of type B—and experts hope each year that the virus does not mutate too far from its ancestors that recipients of the vaccine still have no immunity to it. That is the scenario this year, however, as the Centers for Disease Control and Prevention have reported that a new strain of H3N2, one of the influenza A types, was identified in Brisbane, Australia, too late to substitute the strain into this year’s vaccine.

Authorities still have no idea how severe the problem may become. Of this year’s reported cases of influenza, 34 percent have been versions of the Brisbane strain, the Washington Post reported. In addition, the paper said, a second strain not in the current vaccine, Yamagata, is accounting for about 16 percent of reported flu cases.

This does not mean that the vaccines are entirely useless, though. A Defense Department study conducted after the first incidents of Brisbane were discovered indicated that the vaccines still prevented infection about 50 percent of the time. In years when experts have correctly identified vaccines in advance, the protection rate has been between 70 percent and 90 percent, but 50 percent is still much better than nothing.

Since discovering the new strains, both have been growing in incidence, due mainly to the lack of protection, or just partial protection, even in those already vaccinated. Reports of adult mortality rates are up slightly, but the rate of childhood mortality is low, a sign that the situation may not be all that grave.

To help combat the flu, CDC experts recommend common sense ways to stop its spread: covering of mouths when coughing, washing hands regularly, staying home if sick, still getting vaccinated. They say antiviral drugs can both prevent infections and lessen their severity, and are especially useful in people at high risk for flu complications because of other illnesses. “It wouldn’t be optimal, but there should be a measure of protection, based on our past experience,” the CDC’s chief flu virologist Nancy Cox, told the Post.