Update: influenza activity--United States, 1996-97 season.

In collaboration with the World Health Organization (WHO), its collaborating laboratories, and state and local health departments, CDC conducts surveillance to monitor influenza activity and to detect antigenic changes in the circulating strains of influenza viruses. This report summarizes influenza activity in the United States from September 29 through December 7, 1996, and indicates that influenza activity has increased since mid-November.