Immunogenicity and Persistence of GlaxoSmithKline (GSK) Biologicals' Havrix® in Healthy Adult Subjects Vaccinated at Infancy Under the Hepatitis A Universal Mass Vaccination (UMV) Program in Israel

This study will evaluate the persistence, immunogenicity and safety of Havrix® (hepatitis A vaccine) in adults primed in infancy. The enrolled subjects will be assessed for circulating antibodies against hepatitis A and will also receive a challenge dose of Havrix Adult vaccine. In the present study, the anamnestic response will be assessed 30 days after the challenge dose.


Eligibility Criteria:
Inclusion Criteria:

* Subjects who, in the opinion of the investigator, can and will comply with the requirements of the protocol
* Written informed consent obtained from the subject prior to performing any study specific procedure
* A male or female subject aged 18 to 19 years at the time of enrolment (up to but excluding the 20th birthday)
* Documented administration of 2 doses of Havrix® Junior in the second year of life
* Healthy subjects as established by medical history and clinical examination before entering into the study
* Female subjects of childbearing potential may be enrolled in the study, if the subject:

has practiced adequate contraception for 30 days prior to study vaccine administration, and has a negative pregnancy test on the day of vaccine administration, and has agreed to continue adequate contraception during the entire treatment period and for 2 months after completion of the study vaccine administration

Exclusion Criteria:

* Use of any investigational or non-registered product other than the study vaccine during the period starting 30 days before the dose of study vaccine (Day 29 to Day1), or planned use during the study period
* Any medical condition that in the judgment of the investigator would make intramuscular injection unsafe
* Chronic administration (defined as more than 14 days in total) of immunosuppressants or other immune-modifying drugs during the period starting six months prior to the vaccine dose. For corticosteroids, this will mean prednisone ≥ 20 mg/day, or equivalent. Inhaled and topical steroids are allowed
* Administration of long-acting immune-modifying drugs at any time during the study entry
* Concurrently participating in another clinical study, at any time during the study period, in which the subject has been or will be exposed to an investigational or a non-investigational vaccine/product
* Administration of any hepatitis A vaccine dose, with the exception of the two doses of routine toddler vaccination for the subjects
* Any confirmed or suspected immunosuppressive or immunodeficient condition, based on medical history and physical examination
* History of any reaction or hypersensitivity likely to be exacerbated by any component of the vaccine
* Planned enrolment in the Israel Defense Forces within 30 days of study enrolment or activity that would prohibit the subject to return for Visit 2
* Acute disease and/or fever at the time of enrolment Fever is defined as temperature ≥38.0°C / 100.4°F. The preferred location for measuring temperature in this study will be the oral cavity Subjects with a minor illness without fever may be enrolled at the discretion of the investigator
* Pregnant or lactating female
* Female planning to become pregnant or planning to discontinue contraceptive precautions