Flu shots may not be enough protection against the strain of the bug making its rounds this season.
A Centers for Disease Control and Prevention health advisory issued Wednesday reported that 48 percent of flu virus samples taken last month were closely related to this year's vaccine issued in North America.
"Basically, what the CDC found was that the predominant strain circulating right now is one called H3N2, and just under half of the samples that they tested were a good match with the vaccine. What that means is that the virus has shifted, or what we call viral drift. It's mutated in some way," CBS News medical contributor Dr. Holly Phillips, told CBS This Morning.
The flu shot issued in America has differed from the strain of the bug making its rounds during flu season in the past although Phillips said it's unusual. In the last 22 flu seasons 18 of them had a bug that matched the majority of the most common strains.
Despite the CDC's announcement about the flu shot CDC director Tom Frieden said in a press statement that it's "too soon to tell" if it's going to be a severe flu season.
"It's too early to say for sure that this will be a severe flu season, but Americans should be prepared," said Frieden. "We can save lives with a three-pronged effort to fight the flu: vaccination, prompt treatment for people at high risk of complications, and preventive health measures, such as staying home when you're sick, to reduce flu spread."
The CDC also announced that if you come down with the flu this season the medications Tamiflu (oseltamivir) and Relenza (zanamivir) are effective on nearly all strains of the flu and hinder the virus' ability to reproduce.
