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

Not yet recruiting
Conditions
Hepatitis A
Hepatitis A Virus
Vaccine-Preventable Diseases
Registration Number
NCT07032610
Lead Sponsor
Chiang Mai University
Brief Summary

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.

Detailed Description

Hepatitis A virus (HAV) infection remains one of the most common causes of viral hepatitis among children and adolescents in developing countries, including Thailand. The virus is primarily transmitted through the ingestion of contaminated food or water, or through direct contact with an infected person. HAV typically causes acute hepatitis, ranging from mild illness to severe fulminant hepatitis (acute liver failure), but it does not lead to chronic liver disease. Vaccination is a highly effective strategy to prevent HAV infection and its serious complications.

Currently, two types of HAV vaccines are available in Thailand: (1) the inactivated HAV vaccine (I-HAV), which is administered in two doses six months apart and is approved for use in children aged 12 months and older; and (2) the live-attenuated HAV vaccine (L-HAV), administered as a single dose and approved for children aged 18 months and older. However, neither vaccine has been included in Thailand's Expanded Programme on Immunization (EPI), resulting in suboptimal vaccination coverage across the country.

In 2024, the investigators conducted a randomized, active-controlled, open-label, non-inferiority trial to compare the immunogenicity and safety of the two-dose I-HAV regimen with the single-dose L-HAV in healthy Thai children and adolescents aged 18 months to 18 years. The present study aims to assess the long-term seropositive rate and immunogenicity of anti-HAV antibodies among these participants following a single dose of L-HAV.

Recruitment & Eligibility

Status
NOT_YET_RECRUITING
Sex
All
Target Recruitment
60
Inclusion Criteria
  • Thai children and adolescents who previously participated in the previous RCT study
  • Previously randomized to receive one dose of L-HAV vaccine within the past 1 year (+/- 3 months)
  • Participants and/or caregivers gives written inform consent/assent form
Exclusion Criteria
  • History of acute illness within 4 weeks prior to study enrollment
  • Has a history of illness or a diagnosis consistent with hepatitis A after receiving the live attenuated hepatitis A vaccine as part of participation in a previous research study
  • Has a history of receiving any additional hepatitis A vaccine after participating in the previous research study
  • Presence of fever (body temperature ≥38.0°C), jaundice, or yellowing of the eyes within 4 weeks prior to study enrollment
  • Have any condition that, in the opinion of the site investigator, would compromise the subject's ability to participate in the study

Study & Design

Study Type
OBSERVATIONAL
Study Design
Not specified
Primary Outcome Measures
NameTimeMethod
Anti-HAV seropositivity rate1 year after L-HAV vaccination

Anti-HAV seropositivity rate following a single L-HAV vaccine

Anti-HAV antibody level1 year after L-HAV vaccination

Geometric mean concentration (GMC) of anti-HAV antibodies following a single L-HAV vaccine

Secondary Outcome Measures
NameTimeMethod

Trial Locations

Locations (1)

Department of Pediatrics, Faculty of Medicine, Chiang Mai University

🇹🇭

Chiang Mai, Thailand

Department of Pediatrics, Faculty of Medicine, Chiang Mai University
🇹🇭Chiang Mai, Thailand
Tavitiya Sudjaritruk, MD, PhD
Contact
+66-53-93-6471
tavitiya.s@cmu.ac.th

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