inclusion criteria: 1. healthy participants 18-59 years and 60 years and older, and both males and females should be included; 2. participants who agree to participate in this clinical trial voluntarily and sign the informed consent form, are capable of providing valid identification, understanding and complying with the requirements of the clinical protocol. 3. participants who have been primed with a two-dose inactivated vaccine 6-9 months earlier, and the intervals between the two inactivated vaccines was between 21 and 42 days. 4. for female participants of childbearing potential, effective contraception measures should be used within 2 weeks prior to participation in this study and the results of the pregnancy test must be negative. participants must voluntarily agree to use effective contraceptive measures from the time of signing the informed consent form to the end of the study (effective contraceptive measures including oral contraceptives (excluding emergency contraceptives), injectable or implantable contraceptives, sustained-release topical contraceptives, hormonal patches, intrauterine device, sterilization, abstinence, condoms (for males), diaphragms, cervical caps, etc.).

inclusion criteria: 1. healthy participants 18-59 years and 60 years and older, and both males and females should be included; 2. participants who agree to participate in this clinical trial voluntarily and sign the informed consent form, are capable of providing valid identification, understanding and complying with the requirements of the clinical protocol. 3. participants who have been primed with a two-dose inactivated vaccine 6-9 months earlier, and the intervals between the two inactivated vaccines was between 21 and 42 days. 4. for female participants of childbearing potential, effective contraception measures should be used within 2 weeks prior to participation in this study and the results of the pregnancy test must be negative. participants must voluntarily agree to use effective contraceptive measures from the time of signing the informed consent form to the end of the study (effective contraceptive measures including oral contraceptives (excluding emergency contraceptives), injectable or implantable contraceptives, sustained-release topical contraceptives, hormonal patches, intrauterine device, sterilization, abstinence, condoms (for males), diaphragms, cervical caps, etc.).

inclusion criteria: healthy participants 18-59 years and 60 years and older, and both males and females should be included; participants who agree to participate in this clinical trial voluntarily and sign the informed consent form, are capable of providing valid identification, understanding and complying with the requirements of the clinical protocol. participants who have been primed with a two-dose inactivated vaccine 6-9 months earlier, and the intervals between the two inactivated vaccines was between 21 and 42 days. for female participants of childbearing potential, effective contraception measures should be used within 2 weeks prior to participation in this study and the results of the pregnancy test must be negative. participants must voluntarily agree to use effective contraceptive measures from the time of signing the informed consent form to the end of the study (effective contraceptive measures including oral contraceptives (excluding emergency contraceptives), injectable or implantable contraceptives, sustained-release topical contraceptives, hormonal patches, intrauterine device, sterilization, abstinence, condoms (for males), diaphragms, cervical caps, etc.).

inclusion criteria: healthy participants 18-59 years and 60 years and older, and both males and females should be included; participants who agree to participate in this clinical trial voluntarily and sign the informed consent form, are capable of providing valid identification, understanding and complying with the requirements of the clinical protocol. participants who have been primed with a two-dose inactivated vaccine 6-9 months earlier, and the intervals between the two inactivated vaccines was between 21 and 42 days. for female participants of childbearing potential, effective contraception measures should be used within 2 weeks prior to participation in this study and the results of the pregnancy test must be negative. participants must voluntarily agree to use effective contraceptive measures from the time of signing the informed consent form to the end of the study (effective contraceptive measures including oral contraceptives (excluding emergency contraceptives), injectable or implantable contraceptives, sustained-release topical contraceptives, hormonal patches, intrauterine device, sterilization, abstinence, condoms (for males), diaphragms, cervical caps, etc.).