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 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