Update: influenza activity--United States and Europe, 1993-94 season.

In collaboration with the World Health Organization (WHO) international collaborating laboratories and with state and local health departments in the United States, CDC conducts surveillance to monitor influenza activity and to detect antigenic changes in the circulating strains of influenza viruses. Laboratory surveillance indicates the predominance of influenza type A so far this season. This report summarizes influenza activity in the United States and Europe from mid-September through mid-November 1993.