The flu vaccine may not be very effective this winter, according to U.S. health officials, because of a mutated form of the virus making its way across the nation.
The flu vaccine may not be very effective this winter, according to U.S. health officials, because of a mutated form of the virus making its way across the nation. File photo by Darron Cummings The Associated Press
The flu vaccine may not be very effective this winter, according to U.S. health officials, because of a mutated form of the virus making its way across the nation. File photo by Darron Cummings The Associated Press