Long-term Immunogenicity of L-HAV Vaccine Among Healthy Thai Children and Adolescents

Hepatitis A virus (HAV) remains a common infection among Thai children. Two types of HAV vaccines are available in Thailand: an inactivated vaccine (I-HAV, administered in two doses 6 months apart) and a live-attenuated vaccine (L-HAV, administered as a single dose). However, neither vaccine is currently included in Thailand's Expanded Programme on Immunization (EPI). In 2024, a randomized, active-controlled, open-label, non-inferiority trial was conducted to compare the immunogenicity and safety of the two-dose I-HAV with the single-dose L-HAV in healthy Thai children and adolescents aged 18 months to 18 years. This study aims to evaluate the long-term seropositive rate and immunogenicity of anti-HAV antibodies in this population following a single dose of L-HAV.

NCT Number	NCT07032610
Lead Sponsor	Chiang Mai University Collaborators: Faculty of Medicine, Chiang Mai University
Conditions	Hepatitis A, Hepatitis A Virus, Vaccine-Preventable Diseases
Enrollment	60 participants
Start Date	2025-06-26
Primary Completion	2025-06-28 (estimated)
Study Completion	2026-07-31 (estimated)
Updated on ClinicalTrials.gov	2026-05-22