ABSTRACT
Objective To describe the epidemiological and clinical features of hospitalized people less than 18 years old with influenza A (H1N1)-associated pneumonia and associated risk factors.Methods Through Chinese Reporting System of Influenza A (H 1 N1 ),children aged under 18 years who were hospitalized with laboratory confirmed influenza A (H1N1),case report forms and related information on pneumonia were collected between 1 September 2009 and 4 July 2010.Epidemiological and clinical characteristics including demographics,underlying chronic diseases,treatment,complications and clinical outcome etc.were described.Hospitalized children with pneumonia were compared with those without the above mentioned features,through the univariate and multivariate analysis.Results There were 4240 influenza A (H1N1)-associated hospitalized children with case report forms identified.Of the 4107 influenza A (H1N1) -associated hospitalized children with related information on pneumonia shown in the case report forms,2289 (55.7％) of them had pneumonia.Hospitalized children with influenza A (H1N 1 ) -associated pneumonia had a younger median age (4.9year old),when compared with those without pneumonia (13.1 year old,P＜ 0.0001 ).When compared with the hospitalized children without pneumonia,those hospitalized children with pneumonia were more likely to require intensive care unit care,using mechanical ventilation epuipmentto develop ARDS,respiratory failure or leading to death.Data from multivariate analysis showed that children aged ＜6months(OR=7.08,95％CI:4.15-12.06) between 6 and 23 months(aOR=8.26,95％CI:6.10-11.20) or between 2 to 4 year old (aOR=9.53,95％CI:7.39-12.29) were more likely to develop pneumonia than children aged 5 to 17.Factors as having asthma (OR=12.19,95％ CI:5.18-28.72),cardiovascular disease (OR=5.19,95％ CI:1.94-13.90),chronic renal diseases (OR=2.14,95％ CI:1.02-4.53),chronic hepatic diseases ( OR =5.26,95％ CI:1.40-19.81 ) and allergy (OR=2.54,95％ CI:1.64-3.93 )were significantly associated with influenza A (H1N1) -associated pneumonia.Risk of complication with pneumonia had an increase when oseltamivir treatment was initiated ＞2 days after the onset of illness.Conclusion Pneumonia was a common complication among children hospitalized with influenza A (H1N1).Hospitalized children with influenza A (H1N1)-associated pneumonia were more likely to develop either severe clinical courses or outcomes than those without pneumonia.
ABSTRACT
Objective To understand the infection status of pandemic 2009 H1N1 influenza after the first epidemic wave and to estimate the infected population. Methods Multi-stage stratified random sampling was introduced with 4500 subjects chosen in Guangdong province. 1500 people were selected from 5 districts (3 streets were selected in every district) in Guangzhou city which was representing the large cities. 1500 people were respectively selected from medium-sized city and rural areas, including 20 cities (1 county or district was selected in every city, at least 1 street or town was selected in every county or district respectively and then 1-2 residential area or county was selected in every street or township, respectively). Every sample was selected in accordance with the principle of random sampling, excluding those who had injected with novel H1N1 vaccine. We used hemagglutination inhibition test to understand the serum antibody level of novel H1N1, with title of 1∶40 as positive. Results A number of 4319 specimens, distributed in 21 cities, 25 counties, 85 streets or townships, 144 residential areas, were tested, with an overall positive rate as 22.82% (985/4319). The positive rate of those who had no symptoms of cold since June was 23.47% (471/2007).The positive rate of those who had fever, cough or sore throat was 26.25% (714/2720). The positive rate of those who had influenza-like illness (ILI) was 29.69% (337/1135 ). Conclusion The infection rate in the first epidemic wave of the novel influenza A (H1N1) pandemic in Guangdong province was 22.82%(985/4317). Based on the number of residonts in Guangdong province, the number of natural was estimated to have reached 21.78 million.