Update: influenza activity--United States, 2003-04 season.

Influenza began circulating in the United States unusually early this season, and influenza activity nationwide is expected to increase. Cases of severe disease, including deaths, have been reported in children. This report summarizes influenza activity in the United States during the weeks ending October 4-December 6, 2003. During the week ending December 6, influenza activity was reported to CDC as widespread in 24 states. The early season and the unusually high and persistent demand for vaccine have resulted in a decreasing supply of trivalent inactivated vaccine. Emphasis should be placed on vaccinating persons at high risk for complications from influenza, including healthy children aged 6-23 months. Healthy persons aged 5-49 years who wish to receive vaccine should consider being vaccinated with the intranasally administered live, attenuated influenza vaccine (LAIV), a substantial supply of which remains available.