Please assess the completion status of the following clinical trial:

Trial Title: Antibody Persistence & Immune Memory in Healthy Adults Previously Vaccinated With Twinrix Adult

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:~All subjects must satisfy the following criteria at entry into each of the long-term follow-up visits:~* 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 who received the complete primary vaccination course in the primary study Hepatitis A and B vaccine (HAB), HAB-028 (208127/021).~* Written informed consent obtained from the subject.~All subjects must satisfy the following criteria at entry into the challenge dose phase:~* Subjects who the investigator believes that they can and will comply with the requirements of the protocol.~* A male or female who received the complete primary vaccination course in the primary study HAB-028 (208127/021).~* Written informed consent obtained from the subject.~* Subjects who participated in the long-term follow-up (LTFU) phase of the HAB-028 (208127/021) study and for whom the antibody concentrations were below the cut-off at the last available follow-up time-point.~* Female subjects of non-childbearing potential may be enrolled in 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 vaccination, and~* has a negative pregnancy test on the day of vaccination, and~* has agreed to continue adequate contraception for two months after the administration of the challenge dose.~Exclusion Criteria:~The following criteria should be checked before entry into each of the long-term follow-up visits. If any exclusion criterion applies, the subject must not be included in the study:~* Use of any investigational or non-registered product within 30 days prior to blood sampling.~* Administration of a hepatitis A, hepatitis B or combined hepatitis A and B vaccine outside the study procedures, since the primary study HAB-028 (208127/021).~* History of hepatitis A or hepatitis B infection since the primary study HAB-028 (208127/021).~* Administration of hepatitis A or hepatitis B immunoglobulins and/or any blood products within three months prior to blood sampling.~The following criteria should be checked before the challenge dose is administered. If any apply, the subject must not be included in the challenge dose phase:~* Use of any investigational or non-registered product within 30 days prior to study start or planned use during the study.~* Administration of a hepatitis A, hepatitis B or combined hepatitis A and B vaccine between the last LTFU visit and the challenge dose visit.~* History of hepatitis A or hepatitis B infection between the last LTFU visit and the challenge dose visit.~* History of anaphylactic reactions following the administration of vaccines.~* History of any reaction or hypersensitivity likely to be exacerbated by any component of the vaccines.~* Acute disease and/or fever at the time of enrolment.~* Pregnant or lactating female.~* Female planning to become pregnant or planning to discontinue contraceptive precautions.

- Gender: ALL
- Minimum Age: None
- Maximum Age: None
- Healthy Volunteers: t

Study Arms:
- Twinrix Group (Type: EXPERIMENTAL): Pooled group of subjects from groups who were vaccinated with either Lot 1, Lot 2 or Lot 3 of Twinrix in the primary study according to a 0, 1, 6-Month schedule

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

Answer: outcome: complete