(AL.com) — Experts are predicting a particularly bad flu season this year in part to a mutation that caused this year's vaccine to be less effective.
An analysis published in the New England Journal of Medicine this week estimated that the current vaccine is only about 10 percent effective against this year's flu strain, H3N2. The determination was made after looking at Australia, which uses the same vaccine, and the seriousness of the flu outbreak there.
A flu vaccine in a typical year has an effectiveness rate of between 40 and 60 percent.
According to the Centers for Disease Control, four states - Oklahoma, Louisiana, Georgia and Massachusetts - are currently reporting widespread flu activity.
The flu season generally peaks between late November through March.