title: Description of hospitalized cases of influenza A(H1N1)pdm09 infection on the basis of the national hospitalized-case surveillance, 2009-2010, Japan.
abstract: This study reports the epidemiological characteristics of hospitalized cases of influenza A(H1N1)pdm09 infection analyzed on the basis of surveillance data collected from July 24, 2009, the date on which the hospital-based surveillance of influenza cases was implemented in Japan, to September 5, 2010. During the study period, 13,581 confirmed cases were reported. Among those cases with information regarding the reason for hospitalization, 39% were admitted to hospitals for non-therapeutic purposes such as medical observation and laboratory testing. The overall hospitalization rate was 5.8 cases per 100,000 population when cases hospitalized for non-therapeutic purposes were excluded. While those aged under 20 years accounted for over 85% of hospitalized cases, the largest proportion of fatal cases was observed in those aged over 65 years. The overall case fatality rate for all hospitalized cases was 1.5%. The year-round surveillance for hospitalized influenza-like illness cases was launched in 2011, and it was expected that this surveillance system could add value by monitoring changes in the epidemiological characteristics of hospitalized cases of seasonal influenza.
authors: Infectious Disease Surveillance Center, National Institute of Infectious Diseases; Department of Infections Diseases and Infection Control, Jikei University School Medicine, Tokyo 105-0003, Japan. tomoes@nih.go.jp
authors: Tomoe
authors: T
authors: Shimada
authors: Tomimasa
authors: T
authors: Sunagawa
authors: Kiyosu
authors: K
authors: Taniguchi
authors: Yuichiro
authors: Y
authors: Yahata
authors: Hajime
authors: H
authors: Kamiya
authors: Kumi Ueno
authors: KU
authors: Yamamoto
authors: Yoshinori
authors: Y
authors: Yasui
authors: Nobuhiko
authors: N
authors: Okabe
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D062665:Epidemiological Monitoring; D005260:Female; D006760:Hospitalization; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D053118:Influenza A Virus, H1N1 Subtype / Q000302:isolation & purification*; D007251:Influenza, Human / Q000453:epidemiology / Q000473:pathology* / Q000821:virology*; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009026:Mortality; D055815:Young Adult