Current Study On Evaluation For Hepatitis A Immunization Strategy In Shanghai

Ⅰ.BackgroundHepatitis A was once a high-endemic infectious disease in China. According to Law of the People’s Republic of China on the Prevention and Treatment of Infectious Diseases, hepatitis A belongs to class B infectious diseases and cases of hepatitis A should be reported as part of the National Notifiable Disease Reporting System. It had been a public health concern that the largest documented hepatitis A outbreak in the world occurred in Shanghai in1988. With national socio-economic development and environmental improvement, as well as hepatitis A vaccine strategies, the incidence rates in the whole population were55.69per100,000person-year in the1990and4.24in2008. The incidence of hepatitis A virus (HAV) infection in Shanghai also decreased substantially in the same period.Recently declining seroprevalance of HAV was commonly observed in the global regions. A key effect of the declining rate of HAV transmission in many parts of the world is that the proportion of vulnerable individuals is increasing in the event of HAV outbreak or epidemic. Developed countries are generally low endemic but more susceptible to hepatitis A infection risk. It has been more than20years since the large outbreak of hepatitis A in Shanghai. Immunity acquired from the large outbreak might be reduced and reached a low level. In2008, ministry of Health acclaimed that Vaccines including Hepatitis A had been introduced to expanded program of Immunization. It was freely supplied for Children born after Jul1st,2006. Currently, there is neither data on hepatitis A seroprevalence of Shanghai based on population-based serological survey nor supporting evidence of systemic evaluation for historical immunization strategies. It is difficult to assess, develop and perfect hepatitis A strategies precisely without crucial information above. So it is necessary to carry out population-base serological survey on contact history, risk behavior and exposure, immunization history, together with serum hepatitis A antibody detection to analyze and evaluate on current hepatitis A vaccine application and effect in Shanghai, and further explore hepatitis A immunization strategies in the future.II.Study goal By epidemiological survey and sociological qualitative study, this study is to conduct a systemic evaluation for development and implementation process of hepatitis A immunization strategies and focus on discussing the impacts of policy process of hepatitis A immunization strategies, to evaluate the effectiveness of strategies from the aspect of epidemic shifting pattern, immunization development and serological survey of hepatitis A in a population aged0-30years in Shanghai, together with estimating the policy development in the future, and to provide evidence-based suggestions in order to facilitate the development of policy.Ⅲ.Study contents and methodologies1. Using convenient sampling to select a total of8key policy informants including experts, policy-maker, health manager and doctor to conduct semi-structured in-depth interviews, combined with using of second-hand materials and literature review; survey by questionnaires were conducted in350local residents in two communities in Changnin District in Shanghai to understand the knowledge of hepatitis A and attitude toward hepatitis A vaccine in citizenship. A formative evaluation was concluded from hepatitis A immunization strategies, focusing on influential factors including policy context, process, high risk population, vaccination service and civil society.2. Applying surveillance data analysis to describe longitudinally epidemiological characteristics of hepatitis A in Shanghai during the period of1990-2010, that is20years after hepatitis A pandemic in Shanghai. The effectiveness would be evaluated by epidemic changes.3. Carrying out cross-sectional study for seroprevalence of hepatitis A antibody in0-30years of age population to estimate hepatitis A immunity in population of these age groups and understand immunization effectiveness in children and adolescents, who were always focusing groups for hepatitis A protection. Risk behavior and exposure were also analyzed for natural infection of hepatitis A in young age of life.4. Reporting cases and incidence from National Notifiable Disease Reporting System, surveillance data and annual hepatitis A vaccine distributed doses were all applied to evaluate the comprehensive implementation effectiveness of hepatitis A with technique for order preference by similarity to ideal solution (TOPSIS method) and forecast annual incidence and monthly cases of hepatitis A in the near future by Grey model, exponential smoothing method and autoregressive integrated moving average model (ARIMA model). Meta analysis was applied to estimate long-term seroprotection provided by hepatitis A inactivated vaccine. Evidence-based policy suggestions were proposed to facilitate further effective implementation of policy.Ⅳ.Main study results1. Results of qualitative study and Survey of knowledge and attitudes towards hepatitis A in Shanghai ResidentsWe concluded a formative evaluation for the hepatitis A immunization strategy process from policy context, development, participants and citizenship. There were totally three stages for the development:primary application period, promotion period and Expanded Program of Immunization (EPI) period. Main principles for the development of hepatitis A immunization strategies were listed as following:being suited to the time, evidence-based, safety priority, high risk population first.Population-based seroprevalence surveys and surveillance data play a critical role in supplementing data systems for disease incidence, vaccination coverage in the development of vaccination policy. It is necessary in understanding dynamic epidemic of hepatitis A, combining with laboratory surveillance in cases, contaminating food or water to follow-up for the vaccination policy effectiveness. Those survey results and surveillance data will guide the vaccination policies.Reports from media about the adverse events of vaccination definitely had a great impact on attitude for vaccination, especially in local residents. In our study, we found that in0-18years of age residents, they did not receive hepatitis A vaccine for the reasons of’parents are afraid of adverse effect (21.2%)’,’parents had no idea of how to receive vaccine for their children (33.3%). As for residents with age above18years of age, they didn’t receive hepatitis A vaccine because of high price (16.4%), adverse effect (30.7%) and unknown of how to receive vaccine. So high price, adverse effects and unclear information of vaccination will all lead to low acceptance for hepatitis A vaccination. To prevent and control Hepatitis, which was one of vaccine preventable diseases, it must be made clear that vaccine was not only a way for individual protection, but also for herd immunity. Health education and risk communication are all vital to implement and promote hepatitis A vaccination policy. 2. Results of Epidemiological and surveillance analysis for hepatitis A in ShanghaiIn retrospect of epidemiological characteristics of hepatitis A in past two decades in Shanghai, remarkable changes were observed in incidence and cases distribution by age, profession, region and season. Firstly incident rate of hepatitis A declined significantly from26.07/100,000in1990to0.92/100,000in2010in Shanghai. Cases were summarized for all and it was found a majority of cases belonged to20-40years of age. Dramatic drop in incident rate can be found in each age group. In5-14age group, it decreased from24.02/100,000in1990to0.13/100,000in2010, while in15-24age group it was from45.47/100,000in1990to0.24/100,000in2010. Trend of delay in age of cases could be seen and majority of cases were above40year old in2010. Seasonality is still a feature for hepatitis A epidemic in Shanghai and elevation of case number still could be obvious in January each year, which might be the results of food supply and consumption. Surveillance should be enhanced in this aspect. In2010, retired person instead of farmers ranked first for profession classification in hepatitis A cases number. Students were no more one of top five professional types. Incident rate became almost no difference between urban and rural regions in Shanghai, which might be a result of urbanization. Follow-up documents showed that about2%cases once received hepatitis A vaccine but unknown of whether it was live or killed type.3. Resluts of seroprevalence of hepatitis A virus antibody in a population aged0-30years in ShanghaiThis study was aimed to determine current seroprevalence of Hepatitis A Virus (HAV) antibody in subjects aged0-30years in Shanghai.5515subjects were recruited through random clustering sampling. Basic clinical and demographic information and records of HAV vaccination were acquired by questionnaire interviews and review of immunization records. Serum samples were collected and tested for anti-HAV IgM and total anti-HAV. The overall seroprevalence of total anti-HAV was52.9%. The mean age of the subjects was14.3±7.4years (range:2months to30years). A total of2556subjects (46.3%) were male and2953(53.7%) were female. There was a significant trend for lower anti-HAV seroprevalence in the more elderly age groups (Trend X2=244.1, p<0.0001). A review of the immunization history of the study population indicated that anti-HAV seroprevalence was87.4%(95%CI:85.9%-89.0%) in subjects with HAV vaccination and only37.0%(95%CI:35.5%-38.6%) in those without HAV vaccination or with unknown vaccination history (OR:0.08,95%CI:0.07-0.10). Compared with the results of national viral hepatitis serological survey in1992-1995, seroprevalence in Shanghai had greatly changed.0-18year old children and adolescents were considered priorily in hepatitis A vaccine policy. Total antibody of hepatitis A seropositivity rate were significantly higher in subjects with HAV vaccination (95.2%) than those without HAV vaccination records(32.5%),χ2=997.94, P<0.001, the same to total hepatitis A concentration (t=41.70, P<0.01) in subject of this agegroup. It was evident that HAV vaccination and health education are important for children and adolescence to prevent and control of hepatitis A in Shanghai. In children younger than10years of age, vaccination coverage and seroprevalence of anti-HAV was higher than children and adolescent elder than10years of age. Vaccination coverage also declined with age, trend χ2=1284.81, p<0.001. Consideration of hepatitis A vaccination boosting should be taken for adolescents and young adults for their low vaccination coverage. But further studies are needed to decide how and when should boosting be taken.Seroprevalence of hepatitis A virus antibody in unvaccinated subjects below2year old declined significantly after they were6month old, trend χ2=12.15, p<0.001, which demonstrated the decreasing mother-originated hepatitis A antibody. Based on the immunization record, long-term seroprotection of inactivated and attenuated hepatitis A vaccine was studied in this population. The longer time after vaccination, lower seropositivity rate of hepatitis A antibody in both vaccine types. It seemed seropositivity rate was lower in attenuated vaccine group(84.4%) than inactivated vaccine group (98.6%), χ2=9.37, p=0.02.Multinomial logistic regression was applied in analysis of risk behavior and exposure in0-18unvaccinated subjects. Salad foods (OR:3.881), eating together without food separation in school (OR:3.046) and endoscopy inspection (OR:2.432) were risk factors for the positive total HAV antibody.4. Shanghai hepatitis A Immunization Strategies in the FutureThe implementation effectiveness of hepatitis A vaccination policy showed the increasing tendency as a whole using evaluation of TOPSIS method. Grey model(1,1), exponential smoothing method and ARIMA model were applied in forecasting the annual incident rate or monthly cases of hepatitis A in Shanghai in near future. As a result, it was predicted that declining incidence trend and seasonality will continue. Meta analysis demonstrated that persistence of seroprotection derived from hepatitis A inactivated vaccine would be at least10years and no less than15years when cohort observation studies reported were reviewed.V.Policy recommendationEffective measures of health education should be taken. Knowledge on etiology, severity, vaccine and related policy of hepatitis A should be available in the community, hospital, newspaper, even internet to establish belief of vaccine benefit for both individual and society. Vaccine category, sites of immunization clinics, possible adverse effects, as well as what can be done in case of such adverse events should be explicitly explained and noticed.Improved surveillance with better laboratory confirmation is needed to monitor hepatitis A epidemic and the impact of universal hepatitis A vaccination. Laboratory surveillance, including virological and serological surveillance, plays an important role for vaccination policy development.With the increasing number of susceptible adults to hepatitis A, we suggested further expanded the vaccination program to adolescents, young adults and high risk population after universal program of immunization for preschool children to reinforce the accomplishment in prevention of hepatitis A.More choice for hepatitis A vaccine should be provided for the low vaccination coverage in adults. Combining hepatitis A and B vaccine might be recommended to young adults and elder residents.We suggest that there is no need for boosting vaccine during at least ten years period after primary immunization course, both for inactivated and live hepatitis A vaccine. As for longer time protection, boosting necessity varied among individuals.