Please assess the completion status of the following clinical trial:

Trial Title: A Study to Evaluate The Efficacy, Safety and Immunogenicity of Inactivated SARS-CoV-2 Vaccines (Vero Cell) in Healthy Population Aged 18 Years Old and Above

Study Design Characteristics:
- Allocation: RANDOMIZED
- Intervention Model: PARALLEL
- Observational Model: None
- Primary Purpose: PREVENTION
- Time Perspective: None
- Masking: QUADRUPLE
- Phase: PHASE3
- Number of Arms: 6.0

Eligibility Criteria:
Inclusion Criteria:~1. Healthy subjects aged 18 years old and above.~2. By asking for medical history and physical examination, the investigator judged that the health condition is well.~3. Female subjects of childbearing age are not nursing or pregnant at the time of enrolment (negative urine pregnancy test) and have no family planning within the first 3 months after enrolment. Effective contraceptive measures have been taken within 2 weeks before inclusion.~4. During the whole follow-up period of the study, be able and willing to complete the whole prescribed study plan.~5. With self-ability to understand the study procedures, the informed consent \& voluntarily sign an informed consent form and be able to comply with the requirements of the clinical study protocol.~Exclusion Criteria:~1. Confirmed acute cases of SARS-CoV-2 Infection.~2. Have a history of SARS, MERS infection (self-report, on-site inquiry).~3. Positive urine pregnancy test result.~4. Fever (body temperature \> 37.0 ℃), dry cough, fatigue, nasal obstruction, runny nose, pharyngeal pain, myalgia, diarrhea, shortness of breath and dyspnea occurred within 14 days before vaccination.~5. Axillary body temperature \> 37.0 ℃ before vaccination.~6. Previous severe allergic reactions to vaccination (such as acute allergic reactions, urticaria, dyspnea, angioneurotic edema or abdominal pain) or allergy to known ingredients of inactivated SARS-CoV-2 vaccine have occurred.~7. Has a history of convulsion, epilepsy, encephalopathy or mental illness or family history.~8. With congenital malformations or developmental disorders, genetic defects, severe malnutrition, etc.~9. With severe liver diseases, severe kidney diseases defined as eGFR less than 60, uncontrollable hypertension (systolic blood pressure \>150 mmHg, diastolic blood pressure \> 90 mmHg), diabetic complications, malignant tumors, various acute diseases, or acute attack period of chronic diseases.~10. Has been diagnosed with congenital or acquired immune deficiency, HIV infection, lymphoma, leukemia or other autoimmune diseases.~11. With known or suspected diseases include acute respiratory diseases (e.g. influenza like illness, acute cough, sore throat), severe cardiovascular diseases, liver and kidney diseases, and malignant tumors.~12. Has a history of coagulation dysfunction (e.g. Coagulation factor deficiency, coagulation disease).~13. Receiving anti-TB therapy.~14. Patients receiving immunotherapy or inhibitor therapy within 3 months (continuous oral or infusion for more than 14 days).~15. Live attenuated vaccine is inoculated within 1 month before this vaccination, other vaccines are inoculated within 14 days before this vaccination.~16. Received blood products within 3 months before this vaccination~17. Received other research drugs within 6 months before this vaccination.~18. Other circumstances judged by investigators that are not suitable for this clinical trial.

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

Study Arms:
- Investigational Vaccine 1 (Type: EXPERIMENTAL): Participants will receive 2 doses of the inactivated SARS-CoV-2 vaccine (Vero cell) manufactured by WIBP according to the immunization schedule of D0 \& D21.
- Investigational Vaccine 2 (Type: EXPERIMENTAL): Participants will receive 2 doses of the inactivated SARS-CoV-2 vaccine (Vero cell) manufactured by BIBP according to the immunization schedule of D0 \& D21.
- Placebo (Type: PLACEBO_COMPARATOR): Participants will receive 2 doses of Placebo according to the immunization schedule of D0 \& D21.
- Investigational Vaccine 1b (Type: EXPERIMENTAL): Participants will receive a booster dose of the inactivated SARS-CoV-2 vaccine (Vero cell) manufactured by WIBP after 3 months following two doses of immunization.
- Investigational Vaccine 2b (Type: EXPERIMENTAL): Participants will receive a booster dose of the inactivated SARS-CoV-2 vaccine (Vero cell) manufactured by BIBP after 3 months following two doses of immunization.
- Placebo-b (Type: PLACEBO_COMPARATOR): Participants will receive a booster dose of Placebo after 3 months following two doses of immunization.

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

Answer: outcome: complete