Influenza-related hospitalizations among children in Hong Kong.
BACKGROUND
It has been difficult to define the burden of influenza in children because of confounding by the cocirculation of respiratory syncytial virus (RSV). In Hong Kong, China, the influenza and RSV infection seasons sometimes do not overlap, thus providing an opportunity to estimate the rate of influenza-related hospitalization in a defined population, free from the effects of RSV.


METHODS
In a retrospective, population-based study, we estimated the influenza-associated excess rate of hospitalization among children 15 years old or younger in the Hong Kong Special Administrative Region from 1997 to 1999. Data from a single hospital with intensive use of virologic analyses for diagnosis were obtained to define and adjust for underestimation of the model.


RESULTS
Peaks of influenza and RSV infection activity were well separated in 1998 and 1999 but overlapped in 1997. The adjusted rates of excess hospitalization for acute respiratory disease that were attributable to influenza were 278.5 and 288.2 per 10,000 children less than 1 year of age in 1998 and 1999, respectively; 218.4 and 209.3 per 10,000 children 1 to less than 2 years of age; 125.6 and 77.3 per 10,000 children 2 to less than 5 years of age; 57.3 and 20.9 per 10,000 children 5 to less than 10 years of age; and 16.4 and 8.1 per 10,000 children 10 to 15 years of age.


CONCLUSIONS
In the subtropics, influenza is an important cause of hospitalization among children, with rates exceeding those reported for temperate regions.
Chiu
Susan S
SS
Department of Pediatrics and Adolescent Medicine, University of Hong Kong, Hong Kong, China.
Lau
Yu Lung
YL
Chan
Kwok H
KH
Wong
Wilfred Hing Sang
WH
Peiris
J S Malik
JS
D000208:Acute Disease; D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006723:Hong Kong / Q000453:epidemiology; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D007223:Infant; D007251:Influenza, Human / Q000453:epidemiology*; D008297:Male; D018357:Respiratory Syncytial Virus Infections / Q000453:epidemiology; D012141:Respiratory Tract Infections / Q000453:epidemiology; D012189:Retrospective Studies