NCT06978621

Immunogenicity and Safety of I-HAV in Healthy Thai Children and Adolescents Lacking Protective Antibody After L-HAV

Immunogenicity and Safety of Inactivated Hepatitis A Vaccine in Healthy Thai Children and Adolescents Lacking Protective Antibody Levels After a Single Dose of Live-attenuated Hepatitis A Vaccine

• Status: Recruiting
• Phase: Phase 3
• Study type: Interventional
• Enrollment: 36 (estimated)
• Sponsor: Chiang Mai University · Academic / Other
• Sex: All
• Age: 18 Months – 20 Years
• Healthy volunteers: Accepted

Summary

Hepatitis A virus (HAV) remains a common infection in Thai children. Two HAV vaccines are available: inactivated vaccine (I-HAV, 2 doses) and live-attenuated vaccine (L-HAV, single dose), but neither is included in Thailand's national immunization program. Our previous randomized, active-controlled, open-label, non-inferiority trial trial found that some participants remained seronegative after one L-HAV dose (anti-HAV IgG \<1 S/CO) (preliminary data). This study aims to evaluate the immunogenicity and safety of an additional dose of I-HAV in healthy Thai children and adolescents who did not develop protective antibody levels after a single dose of L-HAV.

Detailed description

Hepatitis A virus (HAV) infection remains a common cause of viral hepatitis among children and adolescents in developing countries, including Thailand. Currently, two types of HAV vaccines are available in Thailand; (1) inactivated HAV vaccine (I-HAV) which is recommended as a 2-dose series administered 6 months apart, approved for use in children aged 1 year and older, and (2) live-attenuated HAV vaccine (L-HAV) which is recommended as a single dose, approved for children aged 18 months and older. However, as neither vaccine is included in Thailand's Expanded Programme on Immunization (EPI), the national vaccination coverage remains suboptimal. In 2024, the investigators conducted a randomized, active-controlled, open-label, non-inferiority trial to compare the immunogenicity and safety of the currently marketed I-HAV and L-HAV in healthy Thai children and adolescents aged 18 months to 18 years. Preliminary results showed that a proportion of participants remained seronegative following a single dose of L-HAV (anti-HAV IgG \<1 S/CO). Based on these findings, the investigators hypothesize that an additional dose of I-HAV may be necessary to achieve adequate seroprotection in this population. Therefore, the aim of this study is to evaluate the immunogenicity and safety of an additional dose of I-HAV in healthy Thai children and adolescents who did not develop protective antibody levels after a single dose of L-HAV.

Conditions

• Hepatitis A
• Hepatitis A Virus
• Vaccine-Preventable Diseases

Interventions

Type	Name	Description
BIOLOGICAL	Inactivated hepatitis A vaccine (I-HAV)	A formaldehyde-inactivated hepatitis A virus (HM175 hepatitis A virus strain) Dose and administration: 0.5 mL intramuscular injection for participants age \<=18 years, and 1.0 mL intramuscular injection for participants age 19 years and above.

Timeline

• Start date: 2025-05-25
• Primary completion: 2025-08-31
• Completion: 2025-09-30
• First posted: 2025-05-18
• Last updated: 2025-06-17

Locations

1 site across 1 country: Thailand