This Study Will Evaluate the Persistence of Hepatitis A Antibodies, 8 Years and 10 Years Later, in Children Who Had Received Havrix at Selected Health Centres of Panama

Long Term Hepatitis A Virus (HAV) Antibody Persistence in Children Vaccinated With 1 Dose and Those Vaccinated With 2 Doses of Havrix in Panama

The purpose of this study is to evaluate the persistence of hepatitis A antibodies, approximately 8 years and 10 years post vaccination with the complete series of Havrix (2 doses) and the partial series completion (1 dose).

The study comprises of two independent cross-sectional surveys (Year 8 and Year 10). The first cross-sectional serosurvey will evaluate the long term persistence of immunity approximately 8 years post vaccine administration and the second cross-sectional study will evaluate long term persistence, approximately 10 years post vaccine administration.

Inclusion Criteria:

• Subjects whose parent(s)/ LAR(s), in the opinion of the investigator, can and will comply with the requirements of the protocol.
• Written informed assent/consent obtained from the subject or subject's parent(s)/ LAR(s) of the subject.
• Available HAV vaccination records.
• Children who have received either 1 or two doses of Havrix at selected health centres of Panama.
• Children with ≥ 7 years and < 10 years between last dose and Persistence Visit 1 (Year 8) and children ≥ 10 years and < 13 years between last dose and Persistence Visit 1' (Year 10).

Exclusion Criteria:

• Child in care.
• Subjects with history of vaccination with other hepatitis A vaccines other than Havrix.
• Subjects with known past history of hepatitis A infection, both without vaccination and after they received the last dose of Havrix (1 dose or the complete 2 dose schedule).