Inclusion Criteria:  Participated in "A Phase III Randomized, Double-blind, Placebo-controlled Clinical Trial in 18 Years of Age and Above to Determine the Safety and Efficacy of ZF2001, a Recombinant Novel Coronavirus Vaccine (CHO cell) for Prevention of COVID-19. Protocol no.: LKM-2020-NCV-GJ01)" and has completed basic immunization with recombinant novel coronavirus vaccine (CHO cells) since 12 months (window period ± 3 months); 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 new coronavirus infection or asymptomatic infection or a history of positive new 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 transplant 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 new coronavirus vaccine (CHO cell) within the past 15 months, has participated in or is participating in other COVID-19 related clinical trials; Researchers believe that any disease or condition in the subject 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.