Walgreen Co. said it's encountering unprecedented demand for seasonal flu shots, delivering more than 1 million vaccinations since it began offering them two weeks ago.

The drug store chain noted that it administered a total of about 1.2 million shots during all of last year's flu season.

"We've seen tremendous response to the early availability of seasonal flu shots," Walgreens CEO Greg Wasson stated.

DEERFIELD, Ill. — Walgreen Co. said it’s encountering unprecedented demand for seasonal flu shots, delivering more than 1 million vaccinations since it began offering them two weeks ago.

Walgreens, which launched its flu vaccine program September 1 at its approximately 7,000 pharmacies and 350 Take Care health clinics nationwide, reported that it topped the 1 million mark in shots on September 15. The drug store chain noted that it administered a total of about 1.2 million shots during all of last year’s flu season.

"We’ve seen tremendous response to the early availability of seasonal flu shots," Walgreens president and chief executive officer Greg Wasson said in a statement. "Consumers are being proactive when it comes to flu prevention, and it’s gratifying to know that our health care professionals are playing such an active role as a valuable resource throughout this flu season."

Walgreens said it has the nation’s largest retail network of certified immunizers, with more than 16,000 pharmacists, nurse practitioners and physician assistants licensed or certified to administer flu shots. The chain is offering seasonal flu shots for $24.99, and Take Care clinics are also offering FluMist nasal spray as an alternative to the shot for $29.99.

On Thursday, Walgreens plans to start distributing up to $1 million in seasonal flu shot vouchers to uninsured adults who visit one of nine Wellness Tour bus locations in select markets nationwide. The vouchers are available on a first-come, first-served basis while supplies last and are good for one seasonal flu shot redeemable at Walgreens pharmacies and Take Care clinics.

Mass retailers of all stripes acted early this year to prepare for flu season amid rising public concern about the need to get immunized, largely spurred by fears about the spread of the H1N1 "swine flu" virus.

In recent weeks, a spate of retailers unveiled plans to provide flu shots in stores and through clinics, ranging from national drug chains CVS Caremark Corp. and Rite Aid Corp. and regional chains such as Kerr Drug, Bartell Drugs and Kinney Drugs to discounters Target Corp. and Kmart to supermarket chains, including Kroger Co., Safeway Inc., Supervalu Inc. and Ahold USA’s Stop & Shop and Giant Food.