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

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 monthafter 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 receivingthe live attenuated hepatitis A vaccine as part of participation in a previousresearch study

• Has a history of receiving any additional hepatitis A vaccine after participating inthe previous research study

• Presence of fever (body temperature ≥38.0°C), jaundice, or yellowing of the eyeswithin 4 weeks prior to study enrollment

• Has underlying conditions including thrombocytopenia, coagulopathy, hemophilia A orB, neurological disorders, immunodeficiency disorders, chronic liver disease, orchronic hepatitis B or C infection

• Has received immunosuppressive agents, immunomodulatory agents, or high-dosecorticosteroids (greater than 2 mg/kg/day or more than 20 mg/day) for more than 14consecutive days within 6 months prior to study enrollment

• Has received blood products or blood components, including immunoglobulins, within 6months 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 aluminumhydroxide, 2-phenoxyethanol, neomycin, formaldehyde, or gentamicin sulfate, or hashistory 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 studyparticipation

• Is concurrently involved in other clinical trials in which receiving aninvestigational vaccine or study drug as part of study participation

• Have any condition that, in the opinion of the site investigator, would compromisethe subject's ability to participate in the study