Hepatitis A vaccine in Indonesia: safeguarding the nation's children and adolescents from overlooked risks

Hepatitis A virus (HAV) is a leading cause of acute viral hepatitis worldwide, particularly in developing countries with poor sanitation, socio-demographic conditions including sexual transmitted diseases. Unlike HAV infection in children, which is generally asymptomatic, infections in adolescents and adults tend to present more severe symptoms. Indonesia is a country with intermediate HAV endemicity, with incidence rates increasing since 2007. Currently, hepatitis A vaccination is not included in the national routine immunisation program, despite the Indonesian Pediatric Society (IDAI) recommending vaccination for children starting at 12 months of age. Two types of HAV vaccines are used. Both show high efficacy in preventing HAV infection, with nearly 100% seroconversion after the second dose. Combined HAV and HBV vaccines also provide long-term protection against both viruses, maintaining high seropositivity rates up to 10 years post-vaccination. However, risks of antibody decline and local and systemic side effects remain, though these are generally well-tolerated.