The influenza vaccine being administered across the nation does not protect against the flu strain that has appeared most often so far this season, according to the Centers for Disease Control and Prevention Director Tom Frieden, MD, MPH.
So far, the H3N2 virus has been detected most frequently in almost all states. "Unfortunately, about half of the H3N2 viruses that we've analyzed this season are different than the H3N2 virus that's included in this year's flu vaccine," Dr. Frieden said during a press call. "They are different enough that we're concerned that protection from vaccinations against these drifted H3N2 viruses may be lower than we usually see."
About 90 percent of the reported flu cases so far this season are H3 viruses. For those, about half are "well matched" with the vaccine. The new, "drifted" version of the flu virus was detected after the World Health Organization made its recommendations for the 2014-15 vaccine.
Despite the concern over this season's vaccine's effectiveness, Dr. Frieden still urged everyone to get a flu shot. "We continue to recommend [the] flu vaccine as the single best way to protect yourself against the flu," he said, noting he and his family have been vaccinated.
Dr. Frieden also emphasized the importance of raising awareness of antiviral medications. Indeed, a recent survey found 43 percent of Americans did not know there are prescriptions available to treat the flu.
"This year, treatment with antiviral drugs is extremely important," he said. "Antiviral drugs are even more important when circulating viruses are different from the vaccine virus."