Early pandemic influenza (2009 H1N1) in Ho Chi Minh City

Rogier van Doorn, Maciej Boni and colleagues analyze the initial H1N1 influenza outbreak in Ho Chi Minh City, Vietnam, including attempts at containment, and establishment of community transmission. To reconstruct the initial outbreak the researchers used reports from the Ministry of Health and clinical and laboratory data for people who were infected with 2009 H1N1 and isolated in hospital. Between April 27 and July 24, three-quarters of a million passengers arriving in the city on international flights were screened at the airport. 200 passengers tested positive for 2009 H1N1 as did 121 non-travelers who were identified during this period after self-reporting illness or through contact tracing. Whilst none of the patients became severely ill, two-thirds of them experienced an influenza-like illness. The average time from starting treatment to clearance of the virus was between 2.6 and 2.8 days for patients who began treatment one to four d ays after becoming ill; whilst for those who started treatment on the first day of illness, the average virus clearance time was 2.0 days. Although the data gathered in this observational study suggest that containment may have delayed establishment of the infection, the researchers were unable to prove that containment worked. Moreover, containment did not prevent eventual community establishment of H1N1 influenza infection.

Citation: Hien TT, Boni MF, Bryant JE, Ngan TT, Wolbers M, et al. (2010) Early Pandemic Influenza (2009 H1N1) in Ho Chi Minh City, Vietnam: A Clinical Virological and Epidemiological Analysis. PLoS Med 7(5): e1000277. doi:10.1371/journal.pmed.1000277 www.plosmedicine.org/article/info%3Adoi%2F10.1371%2Fjournal.pmed.1000277

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