Hepatitis A virus endemicity and vaccine policy, India

Objective: To estimate the age-stratified, hepatitis A virus (HAV) seroprevalence in eight Indian states. Methods: A cross-sectional seroprevalence survey was conducted in 120 rural and 105 urban population clusters across eight Indian states between 12 December 2022 and 28 November 2023. In each cluster, ten participants were randomly selected from each of the age groups: (i) 2 to 4 years; (ii) 5 to 9 years; (iii) 10 to 14 years; (iv) 15 to 30 years; and (v) > 30 years. Serum samples were tested for anti-HAV antibodies. Findings: Overall, the HAV seroprevalence in the five age groups was 33.2% (95% confidence interval, CI: 30.4-36.2), 51.9% (95% CI: 49.0-54.8), 69.2% (95% CI: 66.6-71.8), 89.7% (95% CI: 88.6-90.8) and 97.4% (95% CI: 96.9-97.8), respectively. The female-to-male ratio was 1.52 : 1 and the HAV seroprevalence was 73.0% (4940/6768) in females versus 63.2% (2821/4453) in males. Overall, HAV endemicity was found to be high-intermediate in study groups in Gujarat, Jammu, Karnataka, Punjab and Rajasthan, high in Bihar, intermediate in Assam and low-intermediate in rural Manipur. As the overall seroprevalence for all children younger than 15 years was 51.9%, substantially more than 40% were at risk of HAV infection. Conclusion: Although HAV endemicity varied widely across urban and rural study populations in the eight Indian states, it was generally high-intermediate, providing evidence that HAV endemicity in India has declined in recent years. The study's findings could help Indian policy-makers decide on HAV vaccination for children.