The flu vaccine is doing a better job this year.
Preliminary data suggest it is 59 percent effective. That's a big improvement from last winter's nasty flu season when the vaccine was less than 20 percent effective.
Unlike last year's vaccine, this year's is a good match to the strains making people sick.
It's been a milder flu season so far, though health officials said it has not yet peaked.
Arizona health officials said the flu is "widespread," with more than 3,700 cases reported. Cases have been reported in all 15 counties, but more than half of the statewide total is in Maricopa County.
The numbers were presented Wednesday at a medical meeting in Atlanta.