Please assess the completion status of the following clinical trial:

Trial Title: Challenge Dose of Hepatitis B Vaccine in Subjects Who Previously Received Engerix™-B Vaccine

Study Design Characteristics:
- Allocation: NON_RANDOMIZED
- Intervention Model: SINGLE_GROUP
- Observational Model: None
- Primary Purpose: PREVENTION
- Time Perspective: None
- Masking: NONE
- Phase: PHASE4
- Number of Arms: 2.0

Eligibility Criteria:
Inclusion Criteria:~* Subjects who the investigator believes that they can and will comply with the requirements of the protocol.~* A male or female who had received complete primary vaccination course of hepatitis B vaccine in the primary study~* Written informed consent obtained from the subject and/or parent/guardian of 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 the hepatitis B challenge dose.~Exclusion Criteria:~* Use of any investigational/non-registered drug or vaccine other than the study vaccine within 30 days preceding the hepatitis B vaccine challenge dose or planned use during the study period.~* Chronic administration (more than 14 days) of immunosuppressants other immune-modifying drugs within six months prior to the hepatitis B vaccine challenge dose.~* Planned administration/ administration of a vaccine not foreseen by the study protocol during the period starting from 30 days before the hepatitis B vaccine challenge dose and ending 30 days after.~* Subjects who received an additional dose of hepatitis B vaccine outside the context of the study between the primary vaccination course and the hepatitis B challenge vaccination visit.~* 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 product.~* History of allergic disease or reactions likely to be exacerbated by any component of the vaccine.~* Any confirmed or suspected immunosuppressive or immunodeficient condition, based on medical history and physical examination.~* Acute disease at the time of enrolment.~* Acute or chronic, clinically significant hepatic or renal functional abnormality, as determined by physical examination or laboratory screening tests.~* Administration of immunoglobulins and/or any blood products within the three months preceding the hepatitis B vaccine challenge dose or planned administration during the study period (one month).~* Pregnant or lactating female.~* Female planning to become pregnant or planning to discontinue contraceptive precautions.

- Gender: ALL
- Minimum Age: 17 Years
- Maximum Age: 22 Years
- Healthy Volunteers: t

Study Arms:
- Engerix 2 Doses + Challenge Dose (Type: EXPERIMENTAL): Subjects received 2 doses of Engerix™-B (Month 0 and 6) in the primary study and a single dose of Engerix™-B during the booster study.
- Engerix 3 Doses + Challenge Dose (Type: EXPERIMENTAL): Subjects received 3 doses of Engerix™-B (Month 0, 1 and 6) in the primary study and a single dose of Engerix™-B during the booster study.

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

Answer: outcome: complete