inclusion criteria: 1. adults aged 18 years and above (including boundary values), both female and male. 2. legal identification of the participants shall be provided. 3. the participants have inoculation two doses of inactivated sars-cov-2 vaccine (vero cell) was manufactured by imbcams at least 6 months ago. 4. participants shall understand the content in the informed consent form (icf) and the vaccine for administration, sign the icf voluntarily and are capable of using thermometers and rulers, and filling in diary cards and contact cards as per the requirements. 5. subject shall be able to communicate well with investigators, understand and comply with the requirements of this study. 6. participants with oral temperature ≤ 37.9 ℃. 7. female participants of childbearing potential (defined as any female who has experienced menarche and who is not surgically sterile \[i.e., hysterectomy, bilateral tubal ligation, or bilateral oophorectomy\] or postmenopausal \[defined as amenorrhea at least 12 consecutive months\]) must agree to be heterosexually inactive or consistently use any of the following methods of contraception: a) condoms (male or female) b) diaphragm with spermicide c) cervical cap with spermicide d) intrauterine device e) oral or patch contraceptives f) any country regulatory-approved contraceptive method that is designed to protect against pregnancy g) abstinence, as a form of contraception, is acceptable if in line with the participant's lifestyle (other approaches to abstinence are not acceptable).

inclusion criteria: 1. adults aged 18 years and above (including boundary values), both female and male. 2. legal identification of the participants shall be provided. 3. the participants have inoculation two doses of inactivated sars-cov-2 vaccine (vero cell) was manufactured by imbcams at least 6 months ago. 4. participants shall understand the content in the informed consent form (icf) and the vaccine for administration, sign the icf voluntarily and are capable of using thermometers and rulers, and filling in diary cards and contact cards as per the requirements. 5. subject shall be able to communicate well with investigators, understand and comply with the requirements of this study. 6. participants with oral temperature ≤ 37.9 ℃. 7. female participants of childbearing potential (defined as any female who has experienced menarche and who is not surgically sterile \[i.e., hysterectomy, bilateral tubal ligation, or bilateral oophorectomy\] or postmenopausal \[defined as amenorrhea at least 12 consecutive months\]) must agree to be heterosexually inactive or consistently use any of the following methods of contraception: a) condoms (male or female) b) diaphragm with spermicide c) cervical cap with spermicide d) intrauterine device e) oral or patch contraceptives f) any country regulatory-approved contraceptive method that is designed to protect against pregnancy g) abstinence, as a form of contraception, is acceptable if in line with the participant's lifestyle (other approaches to abstinence are not acceptable).

inclusion criteria: adults aged 18 years and above (including boundary values), both female and male. legal identification of the participants shall be provided. the participants have inoculation two doses of inactivated sars-cov-2 vaccine (vero cell) was manufactured by imbcams at least 6 months ago. participants shall understand the content in the informed consent form (icf) and the vaccine for administration, sign the icf voluntarily and are capable of using thermometers and rulers, and filling in diary cards and contact cards as per the requirements. subject shall be able to communicate well with investigators, understand and comply with the requirements of this study. participants with oral temperature ≤ 37.9 ℃. female participants of childbearing potential (defined as any female who has experienced menarche and who is not surgically sterile [i.e., hysterectomy, bilateral tubal ligation, or bilateral oophorectomy] or postmenopausal [defined as amenorrhea at least 12 consecutive months]) must agree to be heterosexually inactive or consistently use any of the following methods of contraception: a) condoms (male or female) b) diaphragm with spermicide c) cervical cap with spermicide d) intrauterine device e) oral or patch contraceptives f) any country regulatory-approved contraceptive method that is designed to protect against pregnancy g) abstinence, as a form of contraception, is acceptable if in line with the participant's lifestyle (other approaches to abstinence are not acceptable).

inclusion criteria: adults aged 18 years and above (including boundary values), both female and male. legal identification of the participants shall be provided. the participants have inoculation two doses of inactivated sars-cov-2 vaccine (vero cell) was manufactured by imbcams at least 6 months ago. participants shall understand the content in the informed consent form (icf) and the vaccine for administration, sign the icf voluntarily and are capable of using thermometers and rulers, and filling in diary cards and contact cards as per the requirements. subject shall be able to communicate well with investigators, understand and comply with the requirements of this study. participants with oral temperature ≤ 37.9 ℃. female participants of childbearing potential (defined as any female who has experienced menarche and who is not surgically sterile [i.e., hysterectomy, bilateral tubal ligation, or bilateral oophorectomy] or postmenopausal [defined as amenorrhea at least 12 consecutive months]) must agree to be heterosexually inactive or consistently use any of the following methods of contraception: a) condoms (male or female) b) diaphragm with spermicide c) cervical cap with spermicide d) intrauterine device e) oral or patch contraceptives f) any country regulatory-approved contraceptive method that is designed to protect against pregnancy g) abstinence, as a form of contraception, is acceptable if in line with the participant's lifestyle (other approaches to abstinence are not acceptable).

inclusion criteria: 1. adults aged 18 years and above (including boundary values), both female and male. 2. legal identification of the participants shall be provided. 3. the participants have inoculation two doses of inactivated sars-cov-2 vaccine (vero cell) was manufactured by imbcams at least 6 months ago. 4. participants shall understand the content in the informed consent form (icf) and the vaccine for administration, sign the icf voluntarily and are capable of using thermometers and rulers, and filling in diary cards and contact cards as per the requirements. 5. subject shall be able to communicate well with investigators, understand and comply with the requirements of this study. 6. participants with oral temperature ≤ 37.9 ℃. 7. female participants of childbearing potential (defined as any female who has experienced menarche and who is not surgically sterile [i.e., hysterectomy, bilateral tubal ligation, or bilateral oophorectomy] or postmenopausal [defined as amenorrhea at least 12 consecutive months]) must agree to be heterosexually inactive or consistently use any of the following methods of contraception: a) condoms (male or female) b) diaphragm with spermicide c) cervical cap with spermicide d) intrauterine device e) oral or patch contraceptives f) any country regulatory-approved contraceptive method that is designed to protect against pregnancy g) abstinence, as a form of contraception, is acceptable if in line with the participant's lifestyle (other approaches to abstinence are not acceptable).

inclusion criteria: 1. adults aged 18 years and above (including boundary values), both female and male. 2. legal identification of the participants shall be provided. 3. the participants have inoculation two doses of inactivated sars-cov-2 vaccine (vero cell) was manufactured by imbcams at least 6 months ago. 4. participants shall understand the content in the informed consent form (icf) and the vaccine for administration, sign the icf voluntarily and are capable of using thermometers and rulers, and filling in diary cards and contact cards as per the requirements. 5. subject shall be able to communicate well with investigators, understand and comply with the requirements of this study. 6. participants with oral temperature ≤ 37.9 ℃. 7. female participants of childbearing potential (defined as any female who has experienced menarche and who is not surgically sterile [i.e., hysterectomy, bilateral tubal ligation, or bilateral oophorectomy] or postmenopausal [defined as amenorrhea at least 12 consecutive months]) must agree to be heterosexually inactive or consistently use any of the following methods of contraception: a) condoms (male or female) b) diaphragm with spermicide c) cervical cap with spermicide d) intrauterine device e) oral or patch contraceptives f) any country regulatory-approved contraceptive method that is designed to protect against pregnancy g) abstinence, as a form of contraception, is acceptable if in line with the participant's lifestyle (other approaches to abstinence are not acceptable).