[Influenza activity in Japan, 2002/03 season].
Influenza epidemic in 2002/03 season in Japan was second largest among recent 10 seasons. Both influenza A(H3) and B viruses circulated widely this season. Nationally, influenza A(H3) viruses predominated during the first half of the season, but after the week ending February 16, influenza B viruses were reported more frequently than influenza A viruses. Influenza A(H3N2) isolates were reported to be similar to A/Panama/2007/99, the H3N2 component of the 2002/03 influenza vaccine. Antigenic characteristics of epidemic strain of A(H3N2) has not been changed much since 1998/99 season. Considering high herd immunity level to current A(H3N2) virus strain in Japan and higher coverage of immunization with antigenically similar vaccine strains, the size of epidemic in this season was unexpectedly large.
Taniguchi
Kiyosu
K
Infectious Disease Surveillance Center, National Institute of Infectious Diseases.
D017677:Age Distribution; D004196:Disease Outbreaks; D006801:Humans; D009980:Influenza A virus / Q000276:immunology / Q000472:pathogenicity*; D009981:Influenza B virus / Q000276:immunology / Q000472:pathogenicity*; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology; D007564:Japan / Q000453:epidemiology; D013997:Time Factors