Immunogenicity and Safety of Booster Immunization of ZF2001 After Inoculation With Two Doses of BBIBP-CorV

This trial plans to enroll 480 subjects, who will be divided into 3 groups according to the interval between booster immunization and basic immunization: group A (3-4 months), group B (5-6 months), group C (7-9 months) each with 160 subjects (including 120 subjects aged 18-59 years and 40 subjects aged 60 years and above). The recombinant novel coronavirus vaccine (CHO cells) was thoroughly mixed and injected intramuscularly at the deltoid muscle of the upper arm according to the instructions. Blood samples were collected before booster immunization, 14 days, 30 days and 180 days after booster immunization for neutralizing antibody detection. All AEs were collected within 1 month after the booster immunization. Solicited AEs (the following events occurring within 7 days of vaccination) : Adverse events at the inoculation site (local) : pain, pruritus, redness, swelling, rash, induration; Non-inoculated site (systemic) adverse events: fever, headache, fatigue, diarrhea, nausea, vomiting, muscle pain (non-inoculated site), acute allergic reactions, cough. All SAEs were collected within 6 months after the booster immunization.