Vaccination coverage and its determinants of live attenuated hepatitis A vaccine among children aged 24-59 months in 20 rural counties of 10 provinces of China in 2016

Epidemiology and transmission of hepatitis A in Shaanxi (western China) after more than ten years of universal vaccination

Background

Hepatitis A (HepA) vaccination and economic factors can change the epidemiology of HepA. In China, the implementation of free vaccination for children under 1.5 years of age in 2008 has resulted in a decline in the overall incidence of HepA. Nevertheless, further investigation is required to comprehensively understand the epidemiological patterns of HepA in economically disadvantaged regions of China.

Method

In this study, we evaluated the incidence, seroprevalence, and transmission characteristics of HepA in Shaanxi with less economically developed. We obtained data on reported cases of HepA from 2005 to 2020. Blood samples from 1,559 individuals aged 0 to 60 years were tested for anti-hepatitis A (HAV) antibodies. A questionnaire survey and blood sample collection were conducted in two sentinel sites from 2019 to 2021.

Result

Between 2008 to 2020, the number of reported cases of HepA decreased from 3.44/100,000 person-years to 0.65/100,000 person-years, indicating an 81.1% decrease, which was particularly pronounced among younger age groups (0-19 years). From 2015-2020, infections were more likely to occur in people in their 40s and those over the age of 60. Farmers were still the most common occupation of HepA in the last decade. The results of the serological investigation showed the highest anti-HAV seroprevalence was observed in adults aged 39-60 years (94.6%) and those aged 28-38 years (87.8%). The 10-15 years group had the lowest seroprevalence at 49.3%. During the study period, a total of 22 cases were reported by sentinel sites, but the common risk factors (like raw food exposure, travel history, and closed contact with patients) were not identified.

Conclusion

Given the greater severity of illness in the adult population and the ambiguous transmission routine, enhanced surveillance for HepA and evaluations that identify feasible approaches to mitigate the risk of HAV transmission are urgent priorities.

The association between the density of vaccination workers and immunization coverage in Zhejiang province, East China

Background: We aimed to evaluate whether the density of vaccination workers was associated with the immunization coverage in Zhejiang province.Methods: The immunization coverage of measles-containing vaccine (MCV), the third dose of diphtheria, tetanus, and pertussis combined vaccine (DTP3), and the third dose of poliomyelitis vaccine (PV3) was selected as the dependent variables. Immunization coverage data of children aged 13-23 months were taken from the Zhejiang immunization information system (ZJIIS). The aggregate density of vaccination workers was an independent variable in one set of regressions, while the full-time and part-time vaccination workers were adopted separately in other sets.Results: The density of total vaccination workers was positively and significantly associated with the immunization coverage (MCV: AOR = 3.36; DTP3: AOR = 2.68; PV3: AOR = 2.37). However, when the effects of full-time vaccination workers and part-time vaccination workers were assessed separately, we only found that the density of full-time vaccination workers was positively and significantly associated with the immunization coverage (MCV: AOR = 5.59; DTP3: AOR = 4.13; PV3: AOR = 3.28). The proportion of migrant children < 7 years and Land area were found as negative and significant factors for immunization coverage.Conclusions: A higher density of vaccination workers could improve the availability of vaccination services and immunization coverage. We recommended that government or other non-government organization should, apart from vaccine-related assistance, focus their efforts on human resources for vaccination.

Epidemiologic trends of hepatitis A in different age groups and regions of China from 1990 to 2018: observational population-based study

This study characterises changes in the incidence and mortality of hepatitis A in different age groups and provinces of China from 1990 to 2018, and evaluates the effect of the nation-wide expanded programme on immunisation (EPI). A mathematical model was used to estimate the relative change in incidence and mortality in different provinces and age groups. Interrupted time series regression was applied to evaluate the impacts of the inclusion of vaccination in the EPI during 2007–2018. The geographic clustering of hepatitis A incidence was assessed using global Moran's I and changing trends over time were estimated using joinpoint regression analysis. Both the incidence (odds ratio (OR) for overall relative change: 0.86; 95% confidence interval (CI): 0.85–0.87; P < 0.0001) and the mortality rate (OR for overall relative change: 0.84; 95% CI: 0.83–0.85; P < 0.0001) decreased. Most age groups had significant declines in reported incidence over time. The incidence and mortality of hepatitis A significantly reduced after inclusion of hepatitis A vaccine in EPI, showing that the EPI strategy had a continuous effect on the decreasing trend of hepatitis A burden. Increasing the coverage rate of the vaccine and improving hygiene conditions are the key measures for the control of hepatitis A in China.