Extra inactivated hepatitis A vaccine dose for Thai children and adolescents who lack protection after a live hepatitis A vaccine
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
This gives an extra dose of inactivated hepatitis A vaccine to Thai children and adolescents who did not develop protective antibodies after one dose of the live vaccine to see if it produces protection and is safe.
Quick facts
| Phase | Phase 3 |
|---|---|
| Study type | Interventional |
| Enrollment | 36 (estimated) |
| Ages | 18 Months to 20 Years |
| Sex | All |
| Sponsor | Chiang Mai University Academic / other |
| Locations | 1 site (Chiang Mai) |
| Trial ID | NCT06978621 on ClinicalTrials.gov |
What this trial studies
Children and adolescents who previously received a single dose of live-attenuated hepatitis A vaccine (L-HAV) and were found to be seronegative (anti-HAV IgG <1 S/CO) will be offered one additional dose of inactivated hepatitis A vaccine (I-HAV). Investigators will measure antibody levels after vaccination and monitor participants for adverse events to determine immunogenicity and safety. Participants are drawn from a prior randomized trial and must meet eligibility and exclusion criteria, with follow-up visits for blood tests and safety checks. The study focuses on whether a single I-HAV dose can induce seroprotection in those who did not respond to L-HAV.
Who should consider this trial
Good fit: Thai children and adolescents who previously got one dose of live-attenuated HAV within the past year, were seronegative one month after that dose, and can provide consent/assent are the intended participants.
Not a fit: Those who already have protective anti-HAV antibodies, who received additional hepatitis A vaccine doses after the prior study, or who have contraindicating medical conditions are unlikely to benefit from this intervention.
Why it matters
Potential benefit: If successful, an additional I-HAV dose could raise protective antibody levels in children who did not respond to the live vaccine and reduce their risk of hepatitis A.
How similar studies have performed: Inactivated hepatitis A vaccines given as a two-dose series reliably produce protective antibodies in many studies, and using I-HAV to boost non-responders to L-HAV is a logical but less extensively studied approach.
Eligibility criteria
Show full inclusion / exclusion criteria
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 to study enrollment * Has history of allergy to vaccines or any vaccine components, such as aluminum hydroxide, 2-phenoxyethanol, neomycin, formaldehyde, or gentamicin sulfate, or has history of severe allergic reactions (e.g., anaphylaxis) to any vaccines * Women planning for pregnancy, pregnant women or lactating women * Women in childbearing age who cannot use contraceptive methods during study participation * Is concurrently involved in other clinical trials in which receiving an investigational vaccine or study drug as part of study participation * Have any condition that, in the opinion of the site investigator, would compromise the subject's ability to participate in the study
Where this trial is running
Chiang Mai
- Department of Pediatrics, Faculty of Medicine, Chiang Mai University — Chiang Mai, Thailand (Recruiting)
Study contacts
- Principal investigator: Natchaya Kunanitthaworn, MD — Department of Pediatrics, Faculty of Medicine, Chiang Mai University
- Study coordinator: Tavitiya Sudjaritruk, MD, PhD
- Email: tavitiya.s@cmu.ac.th
- Phone: +66-53-936471
How to participate
- Review the eligibility criteria above with your treating physician.
- Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
- Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.