Influenza activity--United States, 1999-2000 season.

Influenza activity was low during October 3-November 6, 1999; influenza virus isolates were reported from 30 states, and four long-term-care facility outbreaks were reported from three states. The predominant viruses isolated were influenza type A(H3N2) viruses. This report summarizes influenza activity in the United States during October 3-November 6, 1999. It also summarizes U.S. influenza surveillance methodology, including the four primary sources of surveillance data, a modification to pneumonia and influenza (P&I) mortality reporting, and discusses detection and control of institutional influenza outbreaks.