Please assess the completion status of the following clinical trial:

Trial Title: Immunogenicity and Safety Study of SCB-2019 Vaccine as a Booster to COVID-19 Vaccine in Adults

Study Design Characteristics:
- Allocation: RANDOMIZED
- Intervention Model: PARALLEL
- Observational Model: None
- Primary Purpose: PREVENTION
- Time Perspective: None
- Masking: QUADRUPLE
- Phase: PHASE3
- Number of Arms: 11.0

Eligibility Criteria:
Inclusion Criteria:~* Male and female participants at least 18 years of age;~* Individuals willing and able to comply with study requirements, including all scheduled visits, vaccinations, laboratory tests, and other study procedures;~* Individuals willing and able to give an informed consent, prior to screening;~* Healthy participants or participants with pre-existing medical conditions who are in a stable medical condition;~* Individuals who received primary vaccination series with one of the selected COVID-19 vaccines (Comirnaty, Vaxzevria, or CoronaVac) ≥3 months prior to enrollment; or received primary series and a booster dose (≥3 months after primary series) of CoronaVac, ≥3 months prior to enrollment.~Exclusion Criteria:~* Individuals with fever \>37.5°C (axillary), or any acute illness at baseline (Day 1) or within 3 days prior to randomization;~* Individuals with laboratory-confirmed SARS-CoV-2 infection at Visit 1 (determined by positive Rapid Antigen Test or RT-PCR);~* Individuals who have received an investigational or licensed COVID-19 vaccine prior to Day 1 (except for primary series with Comirnaty, Vaxzevria, CoronaVac vaccines, or primary and booster dose of CoronaVac), or plan to receive COVID-19 vaccine during the study period;~* Individuals who have a history of severe adverse reaction associated with a vaccine or severe allergic reaction (e.g., anaphylaxis) to any component of the study vaccines;~* Individuals who have received any other investigational product within 30 days prior to Day 1 or intend to participate in another clinical study at any time during the conduct of this study.

- Gender: ALL
- Minimum Age: 18 Years
- Maximum Age: None
- Healthy Volunteers: t

Study Arms:
- Group 1a (primary series: Comirnaty) (Type: EXPERIMENTAL): participants will receive one dose of SCB-2019 vaccine on Day 1
- Group 1b (primary series: Comirnaty) (Type: ACTIVE_COMPARATOR): participants will receive one dose of Comirnaty vaccine on Day 1
- Group 2a (primary series: Vaxzevria) (Type: EXPERIMENTAL): participants will receive one dose of SCB-2019 vaccine on Day 1
- Group 2b (primary series: Vaxzevria) (Type: ACTIVE_COMPARATOR): participants will receive one dose of Vaxzevria vaccine on Day 1
- Group 3a (primary series: CoronaVac) (Type: EXPERIMENTAL): participants will receive one dose of SCB-2019 vaccine on Day 1
- Group 3b (primary series: CoronaVac) (Type: ACTIVE_COMPARATOR): participants will receive one dose of CoronaVac vaccine on Day 1
- Group 4a (primary series and booster dose CoronaVac) (Type: EXPERIMENTAL): participants will receive one dose of SCB-2019 vaccine on Day 1
- Group 4b (primary series and booster dose CoronaVac) (Type: ACTIVE_COMPARATOR): participants will receive one dose of CoronaVac on Day 1;
- Group 4c (primary series and booster dose CoronaVac) (Type: EXPERIMENTAL): participants will receive a half dose of SCB-2019 vaccine on Day 1
- Group 5a (primary series: CoronaVac) (Type: EXPERIMENTAL): participants will receive a dose of 2-vial presentation of SCB-2019 vaccine
- Group 5b (primary series: CoronaVac) (Type: EXPERIMENTAL): participants will receive a dose of 3-vial presentation of SCB-2019 vaccine

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

Answer: outcome: complete