ZF2001 Booster Immunization Clinical Trials of 6 Months After the Completion of Basic Immunization

Inclusion Criteria: * Subjects of 18 years old and above who has completed basic immunization with recombinant novel coronavirus vaccine (CHO cells) since 6 months (window period ± 1 month); * The subjects voluntarily participate in the study, sign an informed consent form, and can provide valid identification, understand and comply with the requirements of the trial protocol; * Female subjects of childbearing age agree to take effective contraceptive measures from the start of the study to 1 month after vaccination. Exclusion Criteria: * A confirmed case of novel coronavirus infection or asymptomatic infection or a history of positive novel coronavirus nucleic acid test; * Patients with uncontrolled lymphoproliferative diseases, unresolved aplastic anemia, active primary immune thrombocytopenia (ITP), uncontrolled coagulopathy, etc; * Patients with malignant tumors before and after surgery, patients undergoing chemotherapy, radiotherapy, immunotherapy, etc.; patients with organ transplantation status; * People with uncontrolled epilepsy and other serious neurological diseases (such as transverse myelitis, Guillain-Barre syndrome, demyelinating diseases, etc.); * Suffering from acute diseases, or acute attacks of chronic diseases, or uncontrolled severe chronic diseases, such as hypertension that cannot be controlled by drugs (systolic blood pressure ≥150mmHg and/or diastolic blood pressure ≥100mmHg); * Previous history of severe allergies to any vaccine, or history of severe allergies to any component of the test vaccine, including aluminum preparations, such as: anaphylactic shock, allergic laryngeal edema, allergic purpura, thrombocytopenic purpura, dyspnea, vascular nerve Sexual edema, etc; * Women who are breastfeeding or pregnant; * In addition to completing the recombinant novel coronavirus vaccine (CHO cell) within the past 7 months, has participated or is participating in other COVID-19 related clinical trials; * Investigators believe that any disease or condition may put the subject at an unacceptable risk; the subject cannot meet the requirements of the protocol; the situation that interferes with the assessment of the vaccine response.