tetano
Editor, Senior Moderator
Am. J. Epidemiol. (2012) doi: 10.1093/aje/kws121 First published online: March 12, 2012
The Epidemiology of Interpandemic and Pandemic Influenza in Vietnam, 2007?2010
The Ha Nam Household Cohort Study I
Peter Horby*,
Le Quynh Mai,
Annette Fox,
Pham Quang Thai,
Nguyen Thi Thu Yen,
Le Thi Thanh,
Nguyen Le Khanh Hang,
Tran Nhu Duong,
Dang Dinh Thoang,
Jeremy Farrar,
Marcel Wolbers and
Nguyen Tran Hien
↵*Correspondence to Peter Horby, Oxford University Clinical Research Unit, National Hospital of Tropical Diseases, 78 Giai Phong Street, Dong Da District, Hanoi, Vietnam (e-mail: peter.horby{at}gmail.com).
Received November 27, 2011.
Accepted January 27, 2012.
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Abstract
Prospective community-based studies have provided fundamental insights into the epidemiology of influenza in temperate regions, but few comparable studies have been undertaken in the tropics. The authors conducted prospective influenza surveillance and intermittent seroprevalence surveys in a household-based cohort in Vietnam between December 2007 and April 2010, resulting in 1,793 person-seasons of influenza surveillance. Age- and sex-standardized estimates of the risk of acquiring any influenza infection per season in persons 5 years of age or older were 21.1% (95% confidence interval: 17.4, 24.7) in season 1, 26.4% (95% confidence interval: 22.6, 30.2) in season 2, and 17.0% (95% confidence interval: 13.6, 20.4) in season 3. Some individuals experienced multiple episodes of infection with different influenza types/subtypes in the same season (n = 27) or reinfection with the same subtype in different seasons (n = 22). The highest risk of influenza infection was in persons 5?9 years old, in whom the risk of influenza infection per season was 41.8%. Although the highest infection risk was in school-aged children, there were important heterogeneities in the age of infection by subtype and season. These heterogeneities could influence the impact of school closure and childhood vaccination on influenza transmission in tropical areas, such as Vietnam.
full article
http://aje.oxfordjournals.org/content/early/2012/03/11/aje.kws121.full
The Epidemiology of Interpandemic and Pandemic Influenza in Vietnam, 2007?2010
The Ha Nam Household Cohort Study I
Peter Horby*,
Le Quynh Mai,
Annette Fox,
Pham Quang Thai,
Nguyen Thi Thu Yen,
Le Thi Thanh,
Nguyen Le Khanh Hang,
Tran Nhu Duong,
Dang Dinh Thoang,
Jeremy Farrar,
Marcel Wolbers and
Nguyen Tran Hien
↵*Correspondence to Peter Horby, Oxford University Clinical Research Unit, National Hospital of Tropical Diseases, 78 Giai Phong Street, Dong Da District, Hanoi, Vietnam (e-mail: peter.horby{at}gmail.com).
Received November 27, 2011.
Accepted January 27, 2012.
Next Section
Abstract
Prospective community-based studies have provided fundamental insights into the epidemiology of influenza in temperate regions, but few comparable studies have been undertaken in the tropics. The authors conducted prospective influenza surveillance and intermittent seroprevalence surveys in a household-based cohort in Vietnam between December 2007 and April 2010, resulting in 1,793 person-seasons of influenza surveillance. Age- and sex-standardized estimates of the risk of acquiring any influenza infection per season in persons 5 years of age or older were 21.1% (95% confidence interval: 17.4, 24.7) in season 1, 26.4% (95% confidence interval: 22.6, 30.2) in season 2, and 17.0% (95% confidence interval: 13.6, 20.4) in season 3. Some individuals experienced multiple episodes of infection with different influenza types/subtypes in the same season (n = 27) or reinfection with the same subtype in different seasons (n = 22). The highest risk of influenza infection was in persons 5?9 years old, in whom the risk of influenza infection per season was 41.8%. Although the highest infection risk was in school-aged children, there were important heterogeneities in the age of infection by subtype and season. These heterogeneities could influence the impact of school closure and childhood vaccination on influenza transmission in tropical areas, such as Vietnam.
full article
http://aje.oxfordjournals.org/content/early/2012/03/11/aje.kws121.full