Director Will Humble says the number of Arizona cases increased by 50 percent this week, causing substantial wait times at several hospitals' emergency departments.
The most common flu strain circulating is H1N1. That's the strain that caused the 2009 pandemic.
Humble says this year's vaccine contains that strain so people who have been vaccinated will be protected.
He says people still can be vaccinated but that it takes about two weeks for full protection.
A list of flu shot providers is available at www.stopthespreadaz.org or by calling Community Information and Referral at 211 from anywhere in the state. For more information about influenza, go to www.azdhs.gov/flu or contact your health care provider or local health department.
Young & middle aged adults are being infected by the flu more this year. It's not too late to get your vaccine. http://t.co/kzN64oRpG9