Hepatitis A virus seroprevalence and acute infection: a five-year retrospective analysis from central part of Turkey

Hepatitis A virus (HAV) remains an important cause of acute viral hepatitis worldwide, with its epidemiology shifting in countries undergoing socioeconomic development. In Turkey, improvements in sanitation and the introduction of routine childhood vaccination in 2012 have reduced early-life exposure, potentially creating a susceptible population among adolescents and young adults. This study aimed to evaluate current HAV seroprevalence, acute infection rates, and age-specific susceptibility patterns.

This retrospective study included individuals tested for anti-HAV IgG and IgM between January 2021 and January 2026 in a tertiary care hospital. Serological analyses were performed using chemiluminescence microparticle immunoassay. Demographic characteristics, clinical unit distributions, and temporal trends were analyzed. Statistical analyses were conducted using SPSS v22.0, with p < 0.05 considered significant.

A total of 7,147 individuals were included (median age: 32 years; 57.8% female). Acute HAV infection (IgM positivity) was detected in only 0.25% of cases, with no significant differences by age or gender. Overall HAV-IgG seropositivity was 63.03%, significantly higher in adults than in children (p < 0.001). The lowest immunity was observed in adolescents aged 15–18 years (12.5%), while seropositivity peaked at 100% in individuals ≥ 60 years. A significant temporal fluctuation was noted, with seropositivity declining to 49.5% in 2022 before rising to 68.5% in 2025 (p < 0.001). Susceptibility to infection was highest among adolescents aged 15–18 years (88.6%) and young adults aged 19–30 years (60.0%).

Despite low acute infection rates, a substantial immunity gap exists, particularly among adolescents and young adults (specifically the 15–30 age cohort). This shift reflects changing endemicity patterns and highlights the need for targeted catch-up vaccination strategies to prevent future outbreaks and severe disease in susceptible populations.

Not applicable.