title: Update: influenza activity--United States and worldwide, 2002-03 season, and composition of the 2003-04 influenza vaccine.
abstract: In collaboration with the World Health Organization (WHO), its collaborating laboratories, state and local health departments, health-care providers, and vital statistic registries, CDC conducts surveillance to monitor influenza activity and to detect antigenic changes in the circulating strains of influenza viruses. During the 2002-03 influenza season, influenza A (H1), A (H3N2), and B viruses co-circulated in the Northern Hemisphere. Human infections with avian influenza A (H5N1) and A (H7N7) viruses were reported in Hong Kong and the Netherlands, respectively. In the United States, the 2002-03 influenza season was mild; influenza A (H1) and B viruses circulated widely, and the predominant virus varied by region and time of season. This report summarizes influenza activity in the United States and worldwide during the 2002-03 influenza season and describes the composition of the 2003-04 influenza vaccine.
mesh_terms: D014943:Global Health; D006801:Humans; D009980:Influenza A virus; D009981:Influenza B virus; D007252:Influenza Vaccines; D007251:Influenza, Human / Q000453:epidemiology* / Q000517:prevention & control; D012621:Seasons; D014481:United States / Q000453:epidemiology; D014611:Vaccination
chemical_list: D007252:Influenza Vaccines