Wyeth said yesterday that it had produced its last traditional flu vaccine, calling the performance of its injectable FluShield product "very disappointing" and throwing its weight behind an alternative vaccine administered through the human nose.

The move could solidify Wyeth's relationship with Gaithersburg-based MedImmune Inc., which is developing a mist vaccine that Wyeth has promised to manufacture.

Madison, N.J.-based Wyeth, one of three companies that supply the seasonal vaccine in the United States, said its decision to pull out of the influenza market "should not impact supply" in 2003, a major worry for public health officials who fear a repeat of last year's vaccine shortage.

Douglas Petkus, a Wyeth spokesman, said the company has consulted with the Centers for Disease Control and has concluded that its competitors -- namely, Aventis Pasteur Inc. of Swiftwater, Pa., and PowderJect Pharmaceuticals PLC, based in England -- will be able to meet the government's request of more than 90 million doses next year. Representatives of the agency could not be reached for comment yesterday.

Wyeth sold only 14 million of the 20 million doses of FluShield it produced last year, prompting its decision to cease making the vaccine, Petkus said.

Analysts said Wyeth's decision is something of an endorsement of FluMist, an experimental nasal spray Wyeth is producing with MedImmune. The vaccine, which has run into delays in gaining government approval, will face a panel of Food and Drug Administration advisers on Dec. 17. A similar panel declined to approve the drug two years ago because Aviron, which later sold FluMist to MedImmune, failed to convince agency officials that there was no link between FluMist and pneumonia. MedImmune shares rose 50 cents yesterday, to $24.15.