Age-stratified prevalence of anti-hepatitis A virus antibodies in four metropolitan Indian cities and recent changes in Pune city.

Background And Objectives: Pune, western India, was earlier identified as hyperendemic for hepatitis A. Subsequently, we noted age and socio-economic status-dependent reduction in hepatitis A virus (HAV) prevalence. To assess the situation in different parts of India, this multicentric, hospital-based, cross-sectional study was conducted in four metropolitan cities in the northern/southern/eastern/western regions.

Methods: As per age group-anti-HAV-positivity-specific sample size calculations (1-40 years), 496 samples/centre were collected from Pune, Kolkata, Chennai and Ludhiana. All samples were tested for anti-HAV antibodies using enzyme-linked immunosorbent assay (ELISA).

Results: Overall, 44.9% of children up to five years of age were anti-HAV antibody-positive (ELISA), with a steady increase reaching 92.9% by the age of 26-40 years. Importantly, 782/1756 (44.5%) of the total population ≤ 15 years was anti-HAV negative and hence susceptible to HAV. The city-wise analysis documented similar patterns with a few differences. According to the World Health Organization (WHO) classification of HAV endemicity, Pune, Chennai and Ludhiana were classified as cities with intermediate endemicity, whereas Kolkata with lower seroprevalence had low endemicity. Compared to the 2011-2012 survey anti-HAV positivity remained unchanged in the other cities except for the rise in Chennai. Apart from age, other risk factors varied in different cities. A comparison of socio-economic-dependent, age-stratified serosurveys conducted during 1982, 1992, 1998, 2017 and 2022 in Pune documented the shift from high to intermediate endemicity in the population with high socio-economic status in 1998 and lower-middle socio-economic strata in 2017.

Conclusion: The lowering of anti-HAV positivity reflects a definite improvement in sanitation and voluntary vaccination, but seems to have slowed down during recent years. Additional, well-defined efforts are necessary.