Vaccination is the best intervention to prevent influenza and its complications. Effective influenza immunization strategy facilitates influenza vaccine coverage to protect the population and reduce disease burden. This paper analyzes related influenza policies from six countries with high vaccination rates and summarizes five common key elements of them. Additionally, we propose the proper immunization strategy of influenza vaccine in China.

Objective: To understand characteristics of demographic, seasonal and spatial distribution of H5N1 cases in major countries of Asia (Indonesia, Cambodia, Vietnam, China) and Africa (Egypt). Methods: Through searching public data resource and published papers, we collected cases information in five countries from May 1st, 1997 to November 6th, 2017, including general characteristics, diagnosis, onset and exposure history, etc. Different characteristics of survived and death cases in different countries were described and χ² test was used to compare the differences among death cases and odds ratio (OR) and 95%CI value was used to compare death risk in different countries. Results: A total of 856 cases were reported in five countries with Egypt had the most cases (44.3%). The highest number of cases were reported in 2015 (18.3%). 53% cases were reported from January to March, and 96.1% of cases had the history of poultry exposure. 64.2% (43 cases) cases in China had live poultry market exposure, but the sick/dead poultry exposure was the major exposure for cases in other four countries. 452 death cases were reported in five countries, and the fatality rate was 52.8%. With Egypt as the reference group, the highest death risk was seen in Indonesia (OR (95%CI): 11.52 (7.46-17.77)), followed by Cambodia (OR (95%CI): 4.27(2.37-7.69)) and China (OR (95%CI): 2.87 (1.73-4.74)). The age distribution of death cases among 5 countries was statistically significant, and the highest fatality rate was in 15-54 years group in Egypt (83.6%, 102 cases), while in Cambodia the highest fatality rate was in 0-14 years group (76.9%, 30 cases). The highest number of deaths were reported in 2006, and 48.3% were reported from January to March. There was difference in exposure routes among 5 countries (χ²=43.85, P=0.001), 63.2% (24 cases) of the death cases in China had live poultry market exposure. 92.9% (79 cases), 83.3% (40 cases) and 100.0% (38 cases) death cases in Indonesia, Vietnam and Camodia had sick/dead poultry exposure, respectively;and 81.6% (31 cases) of the death cases in Egypt had backyard poultry exposure. Conclusion The geographical distribution, seasonal age, gender, exposure matter and outcome of H5N1 cases in five countries were different.

The annual deaths associated with influenza is estimated to be between 290 000 and 650 000,which caused substantial burden to the society.Children have the highest incidence of influenza among all age groups,which can cause overloaded medical visits and a significant increase of hospitalization risk.The severe economic burden includes not only the direct medical costs due to outpatients and hospitalization,but also the indirect burden of school absence of children and work absence of their family members.Annual vaccination is the best measure to prevent influenza,however,influenza vaccination coverage among children in China is very low,and influenza vaccination has not yet been included in the National Immunization Program.Now,the disease burden of influenza and the vaccine usage in children in China were reviewed,and in order to provide evidence for influenza control and prevention.

Objective To estimate the indirect economic burden of disease-related premature deaths in China,2012.Methods 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.Results 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.Conclusion 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.

Seasonal influenza vaccination is the most effective way to prevent influenza virus infection and complications from infection. Currently, China has licensed trivalent inactivated influenza vaccine (IIV3) and quadrivalent inactivated influenza vaccine (IIV4), including split-virus influenza vaccine and subunit vaccine. Except for a few major cities, influenza vaccine is a category Ⅱ vaccine, which means influenza vaccination is voluntary, and recipients must pay for it. To strengthen the technical guidance for prevention and control of influenza and operational research on influenza vaccination in China, the National Immunization Advisory Committee (NIAC) Influenza Vaccine Technical Working Group (TWG), updated the 2014 technical guidelines and compiled the "Technical guidelines for seasonal influenza vaccination in China (2018-2019)" . The main updates in this version include: epidemiology, disease burden, types of influenza vaccines, northern hemisphere influenza vaccination composition for the 2018-2019 season, IIV3 and IIV4 immune response, durability of immunity, immunogenicity, vaccine efficacy, effectiveness, safety, cost-effectiveness and cost-benefit. The influenza vaccine TWG provided the recommendations for influenza vaccination for the 2018-2019 influenza season based on existing scientific evidence. The recommendations described in this report include the following: Points of Vaccination clinics (PoVs) should provide influenza vaccination to all persons aged 6 months and above who are willing to be vaccinated and do not have contraindications. No preferential recommendation is made for one influenza vaccine product over another for persons for whom more than one licensed, recommended, and appropriate product is available. To decrease the risk of severe infections and complications due to influenza virus infection among high risk groups, the recommendations prioritize seasonal influenza vaccination for children aged 6-59 months, adults ≥60 years of age, persons with specific chronic diseases, healthcare workers, the family members and caregivers of infants <6 months of age, and pregnant women or women who plan to become pregnant during the influenza season. Children aged 6 months through 8 years require 2 doses of influenza vaccine administered a minimum of 4 weeks apart during their first season of vaccination for optimal protection. If they were vaccinated in 2017-2018 influenza season or a prior season, 1 dose is recommended. People more than 8 years old require 1 dose of influenza vaccine. It is recommended that people receive their influenza vaccination by the end of October. Influenza vaccination should be offered as soon as the vaccination is available. For the people unable to be vaccinated before the end of October, influenza vaccination will continue to be offered for the whole season. Influenza vaccine is also recommended for use in pregnant women during any trimester. These guidelines are intended for use by staff members of the Centers for Disease Control and Prevention at all levels who work on influenza control and prevention, PoVs staff members, healthcare workers from the departments of pediatrics, internal medicine, and infectious diseases, and staff members of maternity and child care institutions at all levels.

OBJECTIVETo investigate clinical and epidemiological characteristics of hospitalized severe acute respiratory illnesses (SARI) patients under 15 years old registered by sentinel hospitals at 10 cities and risk factors analysis of severe illness.

METHODSThe objects of this study were 2 937 SARI patients under 15 years old registered by sentinel surveillance in internal wards, pediatrics wards and intensive care units (ICU) of 10 sentinel hospitals in 10 cities during the period from December 2009 to June 2014. We also collected case report form (CRF) of them and their throat swabs for influenza testing. The inclusion criteria was hospitalized patients who were admitted by surveillance departments, registered by SARI surveillance system, under 15 years old, meeting SARI case definition and with complete CRF. Rank-sum test was used to compare the difference of age, the duration including from onset to admission, hospital stay and from onset to discharging/death between mild illness and severe illness. Chi-square test was used to compare the difference of demographic characteristics, influenza psoitive rate, vaccination rate of influenza, chronic medical conditions and clinical characteristics between mild illness and severe illness. Logistic regression was used to analysis risk factors associated with severe illness by two stratifications from SARI surveillance protocol (< 2 years old and ≥ 2 years old).

RESULTSAmong 2 937 SARI patients under 15 years old, 97.7% (2 872/2 937) was mild illnesses, and 2.3% (65/2 937) was severe illnesses. 78.8% (2 315/2 937) was under 5 years old. The median ages of severe illness and mild illness were 0.4 and 2.0 years old (U = -6.23, P < 0.001). The proportions of severe illness and mild illness with at least one chronic medical condition were 32.3% (21/65) and 8.4% (240/2 872) (χ² = 45.03, P < 0.001). The positive rate of influenza virus was 6.5% (190/2 937), which was 6.5% (186/2 858) for mild illness and 6.2% (4/65) for severe illness (χ² = 0.08, P = 0.961). The proportion of seasonal influenza vaccination was 1.5% (42/2 853), which was 1.5% (42/2 788) for mild illness and higher than that for severe illness (0) (χ² = 6.09, P = 0.048). For under 2 years old patients, age < 11 months and with at least one chronic medical condition were risk factors for severe SARI illness, and the risk for SARI patients who was 12-23 months and without medical condition was 14.71 (5.35-40.44) and 5.61 (2.96-10.63). For ≥ 2 years old patients, age, with at least one chronic medical condition and seasonal influenza vaccination history have no association with severe illness, OR (95% CI) was 0.92 (0.80-1.05), 0.67 (0.09-5.05) and 0.85 (0.31-2.35), respectively.

CONCLUSIONMost of SARI patients registered by 10 urban sentinel hospitals were patients under 5 years old. Age < 11 months and with at least chronic medical conditions were possible risk factors of severe illness of SARI patients.

Adolescent ; Child ; Child, Preschool ; China ; Chronic Disease ; Cities ; Hospitalization ; Hospitals ; Humans ; Infant ; Influenza, Human ; Orthomyxoviridae ; Respiratory Tract Diseases ; Risk Factors ; Sentinel Surveillance ; Vaccination

Objective 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. Methods 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. Results 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. Conclusion 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.

Objective To estimate the rates due to influenza-associated-excess-hospitalization in children aged 0-14 years in Wuxi city,Jiangsu province in 2005-2010. Methods 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. Results 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. Conclusion Both seasonal and pandemic A(H1N1)pdm influenza caused considerable burden on hospitalization in children aged 0-14 years in Wuxi.

Objective To understand the epidemiological characteristics of influenza outbreaks in China from 2005 to 2013. Methods 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. Results 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 vocations 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. Averagely 30-99 people were involved in an outbreak. Conclusion 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.