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The flu vaccine, which hasn’t worked well to protect Americans against influenza, isn’t helping in Europe, either.

The same mutated version of flu is circulating in Britain and other European countries this winter, and it’s only protected about 3 percent of those vaccinated, British health officials estimate.

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That's even worse than in the U.S., where federal health officials say the vaccine reduced disease risk by 23 percent.

Flu viruses constantly mutate and in any given flu season there will be several making people sick. Usually one dominates, and this year it’s a strain of H3N2 influenza. Unfortunately, it’s not the same one that officials agreed to put into the vaccine cocktail for the 2014-2015 flu season in either Britain or the U.S. Because it takes months to make flu vaccines, it was too late to start over again.

“In a season dominated by early circulation of influenza A(H3N2) virus, we found the overall vaccine effectiveness in preventing medically attended laboratory-confirmed influenza in primary care was only 3.4 percent,” Richard Pebody, of Public Health England, and colleagues wrote in the journal Eurosurveillance.

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-- Maggie Fox