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To understand the epidemiological characteristics of influenza outbreaks in China from 2005 to 2013.The data of influenza-like illness outbreaks involving 10 or more cases were collected through Public Health Emergency Management Information System and National Influenza Surveillance Information System in China, and the influenza outbreaks were identified according to the laboratory detection results. Descriptive epidemiological analysis was conducted to understand the type/subtype of influenza virus and outbreak time, area, place and extent.From 2005 to 2013, a total of 3 252 influenza-like illness outbreaks were reported in the mainland of China, in which 2 915 influenza outbreaks were laboratory confirmed, and influenza A (H1N1) pdm09 virus and influenza B virus were predominant. More influenza outbreaks were reported in the influenza A (H1N1) pandemic during 2009-2010. Influenza outbreaks mainly occurred during winter-spring, and less influenza outbreaks occurred in winter and summer vacations of schools. More influenza outbreaks were reported in southern provinces, accounting for 79% of the total. Influenza outbreaks mainly occurred in primary and middle schools, where 2 763 outbreaks were reported, accounting for 85% of the total. Average 30-99 people were involved in an outbreak.A large number of influenza outbreaks occur during influenza season every year in China, the predominant virus type or subtype varies with season. Primary and middle schools are mainly affected by influenza outbreaks.

To identity the clinical characteristics and severe case risk factors for the adult inpatient cases confirmed of influenza monitored by the sentinel surveillance system for severe acute respiratory infection (SARI) inpatient cases in ten provinces in China.Epidemiology and clinical information surveys were conducted for adult cases (≥ 15 year old) consistent with SARI case definition, who were monitored by SARI sentinel hospitals in ten cities in China from December 2009 to June 2014, with their respiratory tract specimens collected for influenza RNA detection. Adult SARI cases were classified into influenza inpatient group and outpatient group by the detection outcomes, analyzing their demographic information, clinical and epidemiology characteristics respectively, in addition to risk factors for severe inpatient cases.3 071 adult SARI cases were recruited from ten hospitals, including 240 (7.8%) cases of laboratory-confirmed influenza, most of them being A (H1N1) pdm2009 and A (H3N2) sub-types. Age M of the included influenza cases was 63 year old, 47.1% of them being ≥ 65 seniors. 144 (60.0%) cases of the influenza inpatients suffered from at least one chronic underlying condition, and the proportion of emphysema (7.9%) was higher than non-influenza inpatient cases (3.8%), being statistically significant (χ(2) = 3.963, P = 0.047). 19.4% of the women of childbearing age infected of influenza were in pregnancy, and only 1.1% of the 240 influenza cases had been vaccinated against influenza. The proportion of sore throat and dyspnea found among influenza inpatients was higher than inpatients without influenza. 17.4% of the influenza cases were accepted into ICU for treatment, with no statistical significance with non-influenza inpatient cases (P = 0.160). 23.1% of the influenza inpatients received an antiviral drug therapy, a figure higher than the non-influenza inpatient cases (4.8%) (P0.001). 41.5% of the inpatients developed complications, with the proportion of viral pneumonia significantly higher than the non-influenza inpatient cases (P0.001). Asthma (RR = 15.200, 95% CI: 1.157-199.633), immunosuppressive diseases (RR = 5.250, 95% CI: 1.255-21.960), pregnancy (RR = 21.000, 95% CI: 1.734-254.275), time interval from onset to admission less 7 days (RR = 1.673, 95% CI: 1.071-2.614) were identified as risk factors of severely-ill influenza cases.It was found that adult influenza inpatients were mostly ≥ 65 year old seniors. The influenza vaccination rate among the influenza cases was very low, and antivirus drugs were used less than necessary. In this regard, influenza vaccination was recommended for high risk groups of pregnant women, seniors and chronic disease patients on annual basis, while influenza inpatients were advised to use antiviral drugs as early as possible.

To identify clinical characteristics of hospitalized laboratory-confirmed influenza cases of children under 15 years old, and their risk factors of influenza infection.Analyzing the reports of hospitalized laboratory-confirmed influenza cases of children under 15 years old who were detected by the sentinel surveillance systems in 10 provinces from December 2009 to June 2014. Such data as their demographic, medical history, clinical symptoms and signs, treatment and outcome were collected using questionnaires, with their clinical characteristics and their risk factors of influenza infection described.Of the 2 937 severe acute respiratory infection inpatients, 190 (6.5%) were laboratory-confirmed influenza cases. 123 (64.7%) of such confirmed cases were male, and 139 (73.2%) were children under 5 years old, with age median of 3.0 years (IQR: 1.0-5.0 years). 20 (10.5%) of them had at least one chronic medical condition, mostly chronic cardiovascular disease (3.2%), immunosuppressive disease (3.2%), and cancer/tumor (2.6%). Most common clinical symptoms of the cases were fever (92.6%) and cough (88.8%), of which abnormal pulmonary auscultation (51.1%) and abnormal chest X-ray performance (36.1%) were the most common clinical signs. 29 cases (15.8%) had complications, of which pneumonia (15.3%) was most common. 16 cases (8.6%) used antiviral drugs, and 4 cases (2.2%) were admitted into ICU. Risk factor analysis suggested that age6 months (OR = 0.406, 95% CI: 0.203-0.815) was a protective factor against influenza infection; and age 5-9 years old (OR = 2.535, 95% CI: 1.059-6.066) was a risk factor for influenza infection.Hospitalized laboratory-confirmed influenza cases were found mostly in children under 5 years old. Risk exposure for influenza infection varied among age groups.

To estimate the hospitalization rate of severe acute respiratory infection (SARI) cases attributable to influenza in Jingzhou city, Hubei province from 2010 to 2012.SARI surveillance was conducted at four hospitals in Jingzhou city, Hubei province from 2010 to 2012. Inpatients meeting the SARI case definition and with informed consent were enrolled to collect their demographic information, clinical features, treatment, and disease outcomes, with their respiratory tract specimens collected for PCR test of influenza virus.From April, 2010 to September, 2012, 19 679 SARI cases enrolled were residents of Jingzhou, and nasopharyngeal swab was collected from 18 412 (93.6%) cases of them to test influenza virus and 13.3% were positive for influenza. During the three consecutive 2010-2012 flu seasons, laboratory-confirmed influenza was associated with 102 per 100 000, 132 per 100 000 and 244 per 100 000, respectively. As for the hospitalization rate attributable to specific type/subtype of influenza virus, 48 per 100 000, 30 per 100 000 and 24 per 100 000 were attributable to A (H3N2), A (H1N1) pdm2009, and influenza B, respectively in 2010-2011 season; 42 per 100 000 [A (H3N2)] and 90 per 100 000 (influenza B) in 2011-2012 season; 90 per 100 000 [A (H3N2)] and one per 100 000 [influenza B] from April, 2010 to September, 2012. SARI hospitalization caused by influenza A or B occurred both mainly among children younger than five years old, with the peak in children aged 0.5 year old.Influenza could cause a substantial number of hospitalizations and different viral type/subtype result in different hospitalizations over influenza seasons in Jingzhou city, Hubei province. Children less than five years old should be prioritized for influenza vaccination in China.

To estimate the indirect economic burden of disease-related premature deaths in China, 2012.Both human capital approach and friction cost methods were used to compute the indirect economic burden of premature deaths from the following sources: mortality from the national disease surveillance system in 2012, average annual income per capita from the China Statistic Yearbook in 2012, population size from the 2010 China census, and life expectancy in China from the World Health Organization life table.Data from the Human Capital Approach Estimates showed that the indirect economic burden of premature deaths in China was 425.1 billion in 2012, accounting for 8‰ of the GDP. The indirect economic burden of chronic non-communicable diseases associated premature deaths was accounted for the highest proportion(67.1%, 295.4 billion), followed by those of injuries related premature deaths (25.6% , 108.9 billion), infectious diseases, maternal and infants diseases, and malnutrition related deaths (6.4% , 26.9 billion). The top five premature deaths that cause the indirect economic burden were malignancy, cardiovascular diseases, unintentional injuries, intentional injuries, and diseases of the respiratory system. The indirect economic burden of premature deaths mainly occurred in the population of 20-59 year-olds. Under the Friction Cost method, the estimates appeared to be 0.11%-3.49% of the total human capital approach estimates.Premature death caused heavy indirect economic burden in China. Chronic non-communicable diseases and injuries seemed to incur the major disease burden. The indirect economic burden of premature deaths mainly occurred in the working age group.

To estimate the rates due to influenza-associated-excess-hospitalization in children aged 0-14 years in Wuxi city,Jiangsu province in 2005-2010.We collected data on hospitalization due to influenza, pneumonia and other respiratory diseases from fourteen 2nd level or above hospitals in Wuxi, as well as data on influenza virological surveillance in southern China to fit the negative binomial regression models, to estimate the rate on influenza-associated-excess hospitalization.During 2005-2010, an average annual hospitalization rate appeared as 91.6‰ (79.2‰ -99.3‰). Among the total hospitalization eases, respiratory diseases accounted for 54.2%, while both influenza and pneumonia accounted for 38.1%. The average annual influenza- associated-excess-hospitalization rates due to influenza and pneumonia appeared as 1.28‰ (95% CI:0.29‰ -4.84‰), while 2.18‰ (95% CI:0.61‰ -6.79‰) due to respiratory diseases. In 2009, A (H1N1) pdm induced influenza pandemic caused 993 excess hospitalizations due to influenza/pneumonia and 1 042 excess hospitalizations due to respiratory diseases, with rates as 1.14‰ and 1.20‰ respectively.Both seasonal and pandemic A(H1N1)pdm influenza caused considerable burden on hospitalization in children aged 0-14 years inWuxi.

To analyze the viral etiologies of hospitalized pneumonia patients aged less than five years in six provinces during 2009-2012, and to describe the seasonality of the detected viral etiologies.Eight hospitals were selected in six provinces from a national acute respiratory infection surveillance network. Demographic information, clinical history and physical examination, and laboratory testing results of the enrolled hospitalized patients aged less than five years with pneumonia, including respiratory syncytial virus (RSV), human influenza virus, adenoviruses (ADV), human parainfluenza virus (PIV), human metapneumovirus (hMPV), human coronavirus (hCoV)and human bocavirus (hBoV) were analyzed. The viral etiology spectrum of the enrolled patients was analyzed by age-group, year, and seasonality of the detected viral etiologies were described.4 508 hospitalized children less than five years old, with pneumonia from 8 hospitals were included, and 2 688 (59.6%) patients were positive for at least one viral etiology. The most frequent detected virus was RSV (21.3%), followed by PIV (7.1%) and influenza (5.2%), hBoV (3.8%), ADV(3.6%) and hMPV(2.6%). The lowest positive rates in hCoV(1.1%). RSV, influenza, PIV, hBoV and hMPV all showed the nature of seasonality.RSV was a most common viral etiology in the hospitalized young children less than 5 years of age with pneumonia. Prevention measures should be conducted to decrease its severe impact to the young infants and children in China.