A high-profile announcement that this year’s flu vaccine won’t be as effective as hoped was designed largely to help doctors and nurses decide how to deal with patients, and shouldn’t be taken as a reason to skip getting a flu shot, says a state official.

“A flu vaccine offers the best protection against flu and complications of flu,” said Chris Adamsky, chief of the state’s bureau of infectious disease.

On Dec. 4, Centers for Disease Control announced that the strain of flu making most people in the U.S. sick, called H3N2, is not targeted by this year’s vaccine. All of the cases confirmed by New Hampshire state authorities through the end of November – there were only seven of them – involved H3N2, according to state data.

Influenza vaccines must be developed months in advance, based on the best prediction of which strains of flu will be most prevalent. This year’s vaccine mix targets strains based on recommendations made in February.

The H3N2 strain has changed since the vaccine was manufactured in a process known as drift – the CDC says 52 percent of cases tested as of early December were “antigenically different,” meaning antibodies created by the vaccine would probably not combat the virus.

“Drift is a nice word for mutation,” said Adamsky. “We expect some potential for flu strains to drift or change ... although this is very early in the season for such an announcement.”

“Every year is potentially very different and we need to be on alert.”

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