Active — Not RecruitingPhase 3

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

Thailand36 participantsStarted 2025-05-25

Plain-language 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.

Who can participate

Age range

18 Months – 20 Years

Sex

ALL

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.

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 (+/- 2 months) * Have not demonstrate a seropositivity against HAV (anti-HAV IgG \<1 S/CO) at 1 month after L-HAV vaccination * 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 * Has underlying conditions including thrombocytopenia, coagulopathy, hemophilia A or B, neurological disorders, immunodeficiency disorders, chronic liver disease, or chronic hepatitis B or C infection * Has received immunosuppressive agents, immunomodulatory agents, or high-dose corticosteroids (greater than 2 mg/kg/day or more than 20 mg/day) for more than 14 consecutive days within 6 months prior to study enrollment * Has received blood products or blood components, including immunoglobulins, within 6 months prior to study enrollment * Has received other live vaccines within 30 days prior t…

Questions worth asking your doctor

Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.

1Based on my diagnosis and history, is this trial worth exploring for me — or is there a standard treatment we should try first?
2What does this trial's phase tell us about how much is already known about its safety and benefit?
3What would taking part actually involve for me — visits, tests, time, and travel?
4What are the known and possible risks or side effects I should weigh, and how would they be monitored?
5If this trial isn't the right fit, what other options or trials would you suggest I look into?

Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.

Questions for the trial coordinator

The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.

1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?

A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.

What they're measuring

Anti-HAV immunoglobulin G (IgG) seropositivity rate

Timeframe: at baseline (1 year after L-HAV vaccination) and 4 weeks after an additional I-HAV vaccination.

Incidence of adverse events following I-HAV vaccination

Timeframe: immediate and until 4 weeks after an additional I-HAV vaccination.

Trial details

NCT IDNCT06978621

SponsorChiang Mai University

Sponsor typeOTHER

Study typeINTERVENTIONAL

Primary completion2025-06-22

View on ClinicalTrials.gov More Hepatitis A trials