Assessment of Population Immunity to Enteric Hepatitis Viruses in the Population of Belgrade

Hepatitis A (HA) and E (HE) represent a significant global health burden. Despite the development of effective vaccines against hepatitis A virus (HAV) and hepatitis E virus (HEV), outbreaks of acute HA and HE continue to occur worldwide. This study aimed to assess the seroprevalence of anti-HAV and anti-HEV IgG antibodies (Abs) in the population of Belgrade and to analyze their association with socio-demographic and clinical factors.

A cross-sectional study was conducted on a sample of 2533 healthy volunteers in Serbia in May 2024. Participation was voluntary and web-based, leading to an overrepresentation of women and middle-aged adults, while children were underrepresented. Due to this non-probabilistic recruitment, the absolute seroprevalence estimates have limited generalizability to the entire population of Belgrade. Serum samples were tested for anti-HAV and anti-HEV IgG using commercial ELISA kits. The anti-HEV estimate is based on a single ELISA without confirmatory testing and should be interpreted with this limitation in mind. Statistical analysis included confidence interval estimation, chi-square tests, and Spearman's correlation.

Overall seroprevalence was 20.5% (95% CI: 18.9-22.1) for anti-HAV and 22.6% (95% CI: 21.0-24.3) for anti-HEV. A strong, non-linear increase in anti-HAV seroprevalence with age was observed, rising sharply from 2.8% in the 18-29 group to 78.3% in those aged 70+. Anti-HEV seroprevalence also featured a significant positive correlation with age (rs = 0.99, p < 0.0001), increasing from 4.2% in children (1-17 years) to 49.2% in the 70+ group. Men had significantly higher anti-HAV seroprevalence than women (23.1% vs. 19.3%, p = 0.029). Individuals with a history of surgical interventions or blood transfusions had significantly higher odds of being anti-HEV positive (OR = 1.41, p = 0.0005). Vaccination coverage against HAV was low (1.8%), and Abs were detected in only 28.6% of vaccinated individuals.

This study suggests high HEV seroprevalence and an age-polarized HAV seroprevalence in Serbia, indicating a significant shift in the epidemiological landscape while acknowledging the sampling and assay limitations stated above. The findings underscore a growing population susceptible to HAV and highlight the need for reinforced vaccination strategies, improved diagnostics, and targeted public health interventions.