Please assess the completion status of the following clinical trial:

Trial Title: Immunogenicity and Safety of Booster Immunization of COVID-19 Vaccine (Vero Cell), Inactivated (Omicron Variant) in Healthy People Aged 18 Years and Above

Study Design Characteristics:
- Allocation: RANDOMIZED
- Intervention Model: PARALLEL
- Observational Model: None
- Primary Purpose: PREVENTION
- Time Perspective: None
- Masking: DOUBLE
- Phase: PHASE3
- Number of Arms: 9.0

Eligibility Criteria:
Inclusion Criteria:~* Healthy adults aged 18 years and above;~* Subjects completed two doses of the prototype COVID-19 vaccine (CZ strain)(the interval between the first dose and the second dose was 1-2 months)or completed 3 doses of prototype COVID-19 vaccine (CZ strain)over 6 months (the interval between the first dose and the second dose was 1-2 months, and the interval between the second dose and the third dose was 6 months or more);~* The subjects can understand and voluntarily sign the informed consent form;~* Provide legal identification and vaccination certificate of prototype COVID-19 vaccine (CZ strain).~Exclusion Criteria:~* History of SARS-CoV-2 infection(laboratory confirmed);~* Close contact with a confirmed COVID-19 (nucleic acid test or antigen test positive patients)within 14 days prior to randomization;~* Received other COVID-19 vaccine in the past except for two or three doses of prototype vaccine;~* Allergy to vaccines or vaccine/placebo ingredients, and serious adverse reactions to vaccines, such as urticaria, dyspnea, angioneuroedema;~* Autoimmune disease and/or blood disease history (including but not limited to systemic lupus erythematosus, thyroidectomy, autoimmune thyroid disease, any form of malignancy, absence of spleen, functional absence of spleen, or splenectomy for any condition),patients with well-controlled type 1 diabetes can be enrolled;~* Serious chronic diseases, such as serious cardiovascular diseases, hypertension, diabetes, liver and kidney diseases, malignant tumors, etc;~* Severe neurological disease (epilepsy, convulsions or convulsions) or mental illness;~* Diagnosed abnormal blood coagulation function (eg, lack of blood coagulation factors, blood coagulopathy, abnormal platelets) or obvious bruising or blood coagulation;~* Immunosuppressive therapy, cytotoxic therapy, inhaled corticosteroids (excluding allergic rhinitis corticosteroid spray therapy, acute noncomplicated dermatitis superficial corticosteroid therapy) in the past 6 months;~* Long-term history of alcohol or drug abuse;~* Received blood products within 3 months prior to receiving the investigational vaccine, or planning to receive the above treatments during the study period;~* Receipt of other investigational drugs in the past 30 days;~* Receipt of attenuated live vaccines in the past 14 days;~* Receipt of inactivated or subunit vaccines in the past 7 days;~* Onset of various acute or chronic diseases within 7 days prior to the study;~* In case of fever on the day of planned trial vaccine inoculation,axillary temperature \>37.0°C;~* Women who are breastfeeding, pregnant, or planning to become pregnant during the study period (based on subjects' self-reported and urine pregnancy test results);~* Participating in or planning to participate in clinical trials of other vaccines or drugs;~* According to the investigator's judgment, the subject has any other factors that are not suitable for participating in the clinical trial.

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

Study Arms:
- Experimental group aged 18-59 years and received 2 doses of COVID-19 vaccine（CZ strain） (Type: EXPERIMENTAL): 400 participants aged 18-59 years and received 2 doses of COVID-19 vaccine（CZ strain） will receive one dose of inactivated COVID-19 vaccine (Omicron variant).
- Control Group aged 18-59 years and received 2 doses of COVID-19 vaccine（CZ strain） (Type: ACTIVE_COMPARATOR): 200 participants aged 18-59 years and received 2 doses of COVID-19 vaccine（CZ strain） will receive one dose of inactivated COVID-19 vaccine（CZ strain）.
- Experimental group aged 60 years and above and received 2 doses of COVID-19 vaccine（CZ strain） (Type: EXPERIMENTAL): 100 participants aged 60 years and above and received 2 doses of COVID-19 vaccine（CZ strain） will receive one dose of inactivated COVID-19 vaccine (Omicron variant).
- Control Group aged 60 years and above and received 2 doses of COVID-19 vaccine（CZ strain） (Type: ACTIVE_COMPARATOR): 50 participants aged 60 years and above and received 2 doses of COVID-19 vaccine（CZ strain） will receive one dose of inactivated COVID-19 vaccine（CZ strain）.
- Experimental group aged 18-59 years and received 3 doses of COVID-19 vaccine（CZ strain） (Type: EXPERIMENTAL): 400 participants aged 18-59 years and received 3 doses of COVID-19 vaccine（CZ strain） will receive one dose of inactivated COVID-19 vaccine (Omicron variant).
- Control Group aged 18-59 years and received 3 doses of COVID-19 vaccine（CZ strain） (Type: ACTIVE_COMPARATOR): 200 participants aged 18-59 years and received 3 doses of COVID-19 vaccine（CZ strain） will receive one dose of inactivated COVID-19 vaccine（CZ strain）.
- Experimental group aged 60 years and above and received 3 doses of COVID-19 vaccine（CZ strain） (Type: EXPERIMENTAL): 100 participants aged 60 years and above and received 3 doses of COVID-19 vaccine（CZ strain） will receive one dose of inactivated COVID-19 vaccine (Omicron variant).
- Control Group aged 60 years and above and received 3 doses of COVID-19 vaccine（CZ strain） (Type: ACTIVE_COMPARATOR): 50 participants aged 60 years and above and received 3 doses of COVID-19 vaccine（CZ strain） will receive one dose of inactivated COVID-19 vaccine（CZ strain）.
- Historical control group (Type: ACTIVE_COMPARATOR): Backup serum samples will be selected from 250 healthy adult subjects aged 26-45 years who received two doses of inactivated COVID-19 vaccine(CZ strain)from clinical trial of lot-to-lot consistency of an inactivated SARS-CoV-2 Vaccine(Pro-NCOV-4001) to detect neutralizing antibodies against the CZ, Delta and Omicron strains.

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