This flu season is being called the worst in years and has officially been labeled an epidemic by the Centers for Disease Control and Prevention. Experts say many factors are to blame.
Much of that blame is being placed on this year's flu vaccine, which officials now report is only 23 percent effective.
"Most of our patients who've gotten the flu have been vaccinated," a medical expert told WCBS.
A CDC official told The Washington Post that's the lowest percent effective since the agency began keeping track about a decade ago.
And the CDC says H3N2 is considerably harsher than other flu viruses, causing twice as many hospitalizations and deaths.
The flu season also hit hard earlier than normal this year.
"In one week we went from 13 to 22 states being severely effected," Dr. Lolita McDavid said.
The flu generally peaks sometime between December and February, but this year we saw an unusually high number of cases in the beginning of December.
Experts say its too early to tell if the season has already peaked or if the number of cases will continue to grow.
But health officials are hopeful next year's flu season won't be as severe.
Researchers are working on making a universal flu vaccine that would protect against all flu strains, even if they mutate. But that kind of vaccine likely won't be available by next year.