The award follows a protracted five-month review process.
Saatchi & Saatchi will handle creative duties on the direct-to-consumer drug launch, which is estimated to be worth $40 million.
FluMist is the first-ever nasally administered flu vaccine, which contains three strains of live flu virus. Industry observers view it as a possible blockbuster product and not one expected to face competition in the sector until at least 2004.
The Food and Drug Administration has not yet given full approval for the drug. Approval is expected to come in the second quarter of 2003. Wyeth had originally hoped to launch FluMist for the 2002 flu season.
Saatchi officials had no comment on the win, though executives close to the review confirmed that Wyeth informed the agency today.
Wyeth, based in Madison, N.J., and previously known as American Home Products, began an agency search through AAR Partners in August 2002. The company heard pitches from Grey Global Group's Grey Worldwide and Havas' EuroRSCG MVBMS, New York. The two agencies were dropped, with only Interpublic Group of Cos.' Foote, Cone & Belding Worldwide, sibling McCann-Erickson Worldwide and Saatchi making it to the shortlist drawn up in October. Since then, agencies have heard little about the progress of the search.
The drug, co-developed by MedImmune, was expected to launch in fall 2002, but the FDA asked Wyeth to provide more detail about the drug's efficacy in certain age groups.
In December, the company agreed to drop children under the age of 5 from its label. FluMist trialed the nasal spray on 20,000 people. Wyeth's other big-name, over-the-counter consumer drug brands include Advil, Centrum and Robitussin.
The company did not immediately return calls for comment.