Changing sero-epidemiology of hepatitis A in Asia Pacific countries: A systematic review

Objectives: Hepatitis A is a viral liver disease whose prevalence is associated with low socio-economic and hygiene levels due to its faecal–oral transmission. Severity increases with age, and immunity is life-long. Decreased endemicity could result in increased age and severity of cases. A literature review was conducted to describe changes in age-stratified hepatitis A seroprevalence in Asia Pacific countries from 1980 to 2016, and to identify gaps in the literature. The PRISMA guidelines were followed. Methods: The PubMed database was searched for studies on age-specific hepatitis A seroprevalence in 17 Asia Pacific countries. All studies published in the English language, reporting human hepatitis A seroprevalence levels in any age group, were included. Results: Seventy-three publications from 11 countries were identified. A trend of increasing age at first exposure over time was observed, particularly in developed countries such as Japan, Taiwan, Thailand, and Korea, suggesting a transition in terms of endemicity. Conclusions: Extensive gaps in the literature were identified between countries and year of publication, indicating the need for further research. Decreasing hepatitis A exposure and thus immunity conferred during childhood, may render older populations susceptible to infection. The public health and economic value of vaccination against hepatitis A should be assessed within this changing epidemiological context. Keywords: Hepatitis A, Seroprevalence, Asia Pacific, Epidemiolog