The drugstore chain said its seasonal flu-shot clinics will run through October 22 instead of the end of November. The company had planned about 9,000 scheduled clinics.

CVS's MinuteClinics will continue to offer seasonal vaccines at 500 locations in 25 states throughout the flu season, with the supply of vaccines replenished as frequently as possible.

"Supply issues due to manufacturer delays and heavy consumer demand continue to cause shortages of seasonal flu vaccine," CVS spokesman Mike DeAngelis said in an email.

"When we launched our campaign in September, we did not intend to end our flu clinic program in mid-October," he said.

Analysts had predicted CVS could see an earnings gain of up to 14 cents a share due to consumer fears about a swine flu pandemic and a heightened cold season.

DeAngelis said any financial information will be discussed when third-quarter results are released on November 5.

Drugstores have been promoting themselves as destinations for flu shots. The campaigns revolve around the seasonal flu, although drugstores also hope to administer vaccinations for H1N1 flu, or swine flu, once they become more widely available.

WALGREEN SAYS NO SUPPLY TROUBLE

Drugstore rival Walgreen Co said its supply was fine. Rite Aid Corp said some of its order was delayed but it still hopes to get its full allotment.

However, on Monday Rite Aid said seasonal flu-shot clinics in some of its West Coast stores had been canceled by outside provider Mollen Immunization Clinics through mid-December because of shortages. Rite Aid was still providing the vaccine through many of its pharmacies in that region.

A spokeswoman at Sanofi-Aventis SA, one of the world's largest flu vaccine makers, said the company will be able to deliver all the doses it promised, but there is some delay due to H1N1 production and because one of the strains in the seasonal vaccine takes longer to grow. Sanofi said it is producing 50.5 million seasonal doses.

Drugstore chains began offering in-store flu shots in earnest in early September, well ahead of the official start of influenza season on October 4, as determined by the Centers for Disease Control and Prevention.

CVS, with more than 7,000 CVS and Longs Drugs stores, said consumers are getting flu shots at its pharmacies and MinuteClinics at rates far above last year and even above CVS expectations.

The company plans to continue receiving the seasonal vaccines from its suppliers, but due to the continued delays and isolated shortages it will focus on providing the shots through its MinuteClinics, DeAngelis said.

Walgreens plans to provide 5 million seasonal flu shots and has already offered about 4.5 million, spokesman Michael Polzin said. "We got our full supply and we've given out most of its already."

Rite Aid spokeswoman Cheryl Slavinsky said the delays were caused by manufacturers switching production to the H1N1 vaccine, and those delays would be addressed when suppliers switched back to production of the seasonal vaccine.

"We have spot shortages here and there," she said. "We still have not gotten all of our shipment ordered from the manufacturer in the spring.

"Our manufacturer has not given us any indication that our full order won't be fulfilled," she added. "It's just delayed."

CVS shares rose 1.2 percent to $37.84 on Thursday afternoon. Walgreen gained 2.2 percent and Rite Aid slipped 0.6 percent.