On October 5, 2004, CDC was notified by Chiron Corporation that none of its inactivated influenza vaccine (Fluvirin®) would be available for distribution in the United States for the 2004–05 influenza season. At that time, CDC, in coordination with the Advisory Committee on Immunization Practices (ACIP), issued interim recommendations to direct available inactivated influenza vaccine to persons in certain priority groups. CDC has been working with Aventis Pasteur, Inc., to distribute the remaining supply of its inactivated influenza vaccine Fluzone® so that it reaches persons in the priority groups established on October 5. In addition, on December 7, the U.S. Department of Health and Human Services announced that up to 4 million doses of the GlaxoSmithKline influenza vaccine Fluarix®, authorized for use by the Food and Drug Administration under an Investigational New Drug (IND) application, would be available to help alleviate the influenza vaccine shortage this season.

The primary goal of the annual influenza vaccination recommendations by CDC and ACIP is to reduce the risk for complications from influenza among persons who are most vulnerable. This year, the reduced national supply of inactivated influenza vaccine led CDC and ACIP to issue interim influenza vaccination recommendations that were more restrictive than usual. Since the interim recommendations were issued on October 5, the influenza vaccine supply and demand situation has continued to evolve in the United States such that some, but not all, local areas appear to have adequate supplies to meet the demand for vaccine from persons in the interim priority groups. This has resulted in unused vaccine in some areas of the country.

Influenza disease activity in the United States has remained relatively low but is expected to increase during the weeks ahead. In addition, influenza vaccination coverage among this season´s interim priority groups is lower than it has been in recent influenza seasons. Given these considerations, CDC recommends that aggressive efforts should continue to reach unvaccinated persons in high-risk priority groups and use available vaccine to vaccinate such persons. Adequate time remains for persons in these priority groups to receive the benefits of vaccination before influenza begins to widely circulate in most communities. CDC will continue to allocate available vaccine to states that have insufficient supplies of vaccine to reach these priority groups.