ABSTRACT
Objective To study the epidemiological characteristics on the clustering nature of pandemic (H1N1) 2009 in China.Methods Time and place distribution of pandemic (H1N1) 2009on the nature of clustering through data from Public Health Emergency Management Information System were described.Results As of August 10,2010,2773 pandemic (H1N1) 2009 clusters,a total of 77363 cases (including 20 deaths) were reported in the mainland of China.The most reported number of clusters was from schools and kindergartens with the total number of 2498 (accounted for 90.08％ of the total number).Middle schools appeared the have the most clusters (1223,accounting for 48.96％ ).The number of clusters reported in the southern provinces (cities) accounted for 77.03％ of the total,and was more than that in the northern provinces (cities).Two reported peaks in the southern provinces (cities) were in June and November,2009,respectively.There was only one reported peakin the northern provinces in September,2009.Conclusion Time and place distribution characteristics on the clusters of pandemic (H1N1) 2009 were similar to the seasonal influenza,but the beginning of winter peak was much earlier and intensity of reporting was much higher on the clusters of pandemic (H1N1 ) 2009 than that of seasonal influenza.
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.