Update: influenza activity--United States, 2004-05 season.

This report summarizes influenza activity in the United States during October 3, 2004-March 26, 2005, updates the previous summary, and describes the composition of the 2005-06 influenza vaccine. Influenza activity was moderate in the United States overall, but varied by region. Preliminary data collected through the seven components of the CDC Influenza Surveillance indicate that national influenza activity peaked in early-February.