Please assess the completion status of the following clinical trial:

Trial Title: Immune Response to Hepatitis B Vaccine Challenge Dose in Subjects Who Received a Primary Neonatal Hepatitis B Vaccine.

Study Design Characteristics:
- Allocation: None
- Intervention Model: SINGLE_GROUP
- Observational Model: None
- Primary Purpose: PREVENTION
- Time Perspective: None
- Masking: NONE
- Phase: PHASE4
- Number of Arms: 1.0

Eligibility Criteria:
Inclusion Criteria:~* Subjects who the investigator believes that they can and will comply with the requirements of the protocol should be enrolled in the study.~* A male or female adult who received the complete neonatal primary vaccination course of hepatitis B vaccine in primary study approximately 20 years earlier.~* Documented level of anti-HBs antibody concentrations \< specified concentration at the previous long-term time point for which serological results are available for that subject.~* Written informed consent obtained from the subject.~* Healthy subjects as established by medical history and clinical examination before entering into the study.~* If the subject is female, she must be of non-childbearing potential or if she is of childbearing potential, she must practice adequate contraception for 30 days prior to vaccination, have a negative pregnancy test and continue such precautions for 2 months after completion of the hepatitis B challenge dose.~Exclusion Criteria:~* Chronic administration (defined as more than 14 days) of immunosuppressants or other immune-modifying drugs within six months prior to the hepatitis B vaccine challenge dose.~* Administration of a vaccine not foreseen by the study protocol during the study period.~* Administration of immunoglobulins and/or any blood products during the study period.~* Drug and/or alcohol abuse.

- Gender: ALL
- Minimum Age: 20 Years
- Maximum Age: 21 Years
- Healthy Volunteers: t

Study Arms:
- Group Engerix™-B (Type: EXPERIMENTAL): Subjects received a dose of Hepatitis B vaccine approximately 20 years after the primary neonatal vaccination

Based on this trial design, predict the completion outcome and termination type (if applicable).