Transmission potential of the new influenza A(H1N1) virus and its age-specificity in Japan.

H. Nishiura, C. Castillo-Chavez, M. Safan, G. Chowell

Research output: Contribution to journalArticle

179 Scopus citations

Abstract

On 16 May 2009, Japan confirmed its first three cases of new influenza A(H1N1) virus infection without a history of overseas travel, and by 1 June, 361 cases, owing to indigenous secondary transmission, have been confirmed. Of these, 287 cases (79.5%) were teenagers (i.e. between 10 and 19 years of age). The reproduction number is estimated at 2.3 (95% confidence interval: 2.0, 2.6). The average number of secondary transmissions involving minors (those under 20 years of age) traced back to infected minors is estimated at 2.8. That is, minors can sustain transmission even in the absence of adults. Estimates of the effective reproduction number Rt moved below 1 by 17 May. Active surveillance and public health interventions, including school closures most likely have contributed to keeping Rt below one.

Original languageEnglish (US)
JournalEuro surveillance : bulletin européen sur les maladies transmissibles = European communicable disease bulletin
Volume14
Issue number22
DOIs
StatePublished - Jun 4 2009
Externally publishedYes

ASJC Scopus subject areas

  • Epidemiology
  • Public Health, Environmental and Occupational Health
  • Virology

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