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WASHINGTON — A House investigative panel will press federal health officials on Thursday to find out what they’ve done to make sure this year’s flu vaccine works — after last year’s vaccine turned out to be the least effective in years.

The hearing by the House Energy and Commerce Oversight and Investigations subcommittee will feature top officials from the Centers for Disease Control and Prevention and the Food and Drug Administration, both of which have roles in the nationwide flu vaccination efforts.

Lawmakers, particularly the Republicans who are in charge of the subcommittee, are expected to question the officials on two key concerns: They’re worried that CDC didn’t watch the Southern Hemisphere’s flu season closely enough — Australia, for example, had its worst flu outbreak in 20 years. And they’re concerned about British researchers’ warnings that, for technical reasons, the vaccine that’s being developed now could be less effective than health officials expect.


A committee aide who previewed the hearing for STAT noted that while federal agencies have greatly improved their response to seasonal flu since last year’s tough winter, that’s not going to end the questions on other aspects of preparedness.

“We think the Centers for Disease Control and Prevention has made a lot of progress, but we still have concerns,” said a committee aide.


Last winter’s influenza strain was unusually harsh, and the vaccine that the Department of Health and Human Services helped develop was a bad match. According to the subcommittee report that’s being released with the hearing, the 2014-15 vaccine had the worst effectiveness rate in four to five years.

The flu shot did not protect well against the dominant H3N2 A strain of influenza, which mutated after the vaccine-production process began. Given the long lead time necessary to manufacture the vaccine, public health agencies were unable to modify it and restart production.

The vaccine worked for just 19 percent of the overall US population, and even less so for certain subgroups. The effectiveness rate was only 12 percent for 18- to 49-year-olds, and just slightly better, at 14 percent, for those 50 years or older.

As a result, more people were hospitalized with the flu last year than anytime since the CDC started tracking hospital admissions in 2005. The disease was especially dangerous among the elderly.

The witnesses at the hearing will include Dr. Anne Schuchat, principal deputy director of the CDC, which makes recommendations on who should be vaccinated and tracks the spread of the flu, as well as Dr. Karen Midthun from the FDA, which selects the flu strains to include in the vaccines.

Lawmakers will also hear from Dr. Robin Robinson of the Biomedical Advanced Research and Development Authority, which funds vaccine research and development, and Dr. Carole Heilman, director of the National Institute of Allergy and Infectious Diseases, which also supports and conducts influenza research.

The concern about the effectiveness of this year’s vaccine comes from British researchers who are worried about a phenomenon called “egg adaptation,” according to committee aides. Because hen eggs are used to propagate the viruses that the World Health Organization sends to US vaccine manufacturers, and because most of the vaccine supply is produced in eggs, the researchers worry that its effectiveness could be weakened by any mutations that occur when the vaccine is adapted to make it grow in eggs.

Influenza is a major cause of death in the United States, according to the CDC. Roughly 20 percent of the population catches it. The CDC estimated more than 53,000 influenza deaths in 2010, the last year for which statistics are available.