About a third of Minnesota's confirmed flu cases this year do not appear to match the influenza vaccine.
The Minnesota Department of Health said its findings vary somewhat from a vaccine mismatch reported today in Wisconsin.
The Centers for Disease Control and Prevention said a review of flu cases from Wisconsin show that two of the three flu strains included in this year's vaccine are not good matches. In particular, the review detected a significant vaccine mismatch with a B-strain of the virus that has been circulating in Wisconsin.
The Health Department said in Minnesota the patient samples that didn't match the vaccine are mostly A-strains.
Immunizations expert Kris Ehresmann said the mismatch is unfortunate, but it shouldn't cause patients to lose faith in the vaccine.
"This is not what we want to stick in people's minds," Ehresmann said. "I think what's important for people to keep in mind is that, even though this was definitely a sub-optimal year which is disappointing, the interim study that was done in Wisconsin found that the vaccine was still 44 percent effective in protecting against any influenza."
Minnesota's flu season typically lasts through the end of April.