Tiered use of inactivated influenza vaccine in the event of a vaccine shortage.

The United States has experienced disruptions in the manufacture or distribution of inactivated influenza vaccine during three of the last five influenza seasons. Delays in delivery of influenza vaccine or vaccine shortages remain possible, in part, because of inherent time constraints in manufacturing the vaccine, given the annual updating of influenza vaccine strains and uncertainties regarding vaccine supply (including licensure of new vaccine preparations). Although total vaccine supply for the 2005-06 influenza season is not yet known, the minimum anticipated supply is approximately 58-60 million doses of inactivated vaccine and 3 million doses of live, attenuated vaccine. This estimated supply is similar to that available during the 2004-05 season and would be adequate to satisfy historical demand for influenza vaccine among persons considered by the Advisory Committee on Immunization Practices (ACIP) to be at high risk for serious complications associated with influenza virus infection, health-care workers, and household contacts of children aged <6 months. These groups were prioritized for influenza vaccination in 2004-05. Additional doses of inactivated influenza vaccine might be available for the U.S. market in 2005-06, but this cannot yet be confirmed. Availability of additional vaccine would allow for expansion of the priority groups and, preferably, vaccination of all persons who desire it.