inclusion criteria: * healthy people aged 3 years and above who have completed two or three doses of coronavac at least 3 months (≥ 90 days) before (3-8 weeks interval for the first and second dose of coronavac, and ≥3 months interval for the second and third dose); * participants (and/or their legal guardians for pediatric population) are able to understand and sign the informed consent voluntarily; * pregnancy and contraception: female participants of childbearing potential (post-menarche and pre-menopause that has not been undergone any sterilization surgery), who have a negative pregnancy test on the day of booster vaccination in the present study, has practiced adequate contraception or has abstained from all activities that could result in pregnancy for at least 28 days prior to the day of vaccination, and agree to continue adequate contraception through 3 months following the booster vaccination and are not currently breastfeeding; male participants of childbearing potential who agree to use adequate contraception through 3 months following the booster vaccination (and/or your female partner agree to use an acceptable method of birth control), which include refrain from donating sperm; note 1 :adequate contraception is defined as consistent and correct use of an approved contraceptive method in accordance with the product label. for example: * barrier method (such as condoms, diaphragm, or cervical cap) used in conjunction with spermicide * intrauterine device * prescription hormonal contraceptive taken or administered via oral (pill), transdermal (patch), subdermal, or im route * sterilization of a female participant's monogamous male partner prior to entry into the study note 2 : periodic abstinence (eg, calendar, ovulation, symptothermal, post-ovulation methods) and withdrawal are not acceptable methods of contraception. * participants are able to comply with study procedures based on the assessment of the investigator; * participants willing to provide verifiable identification (following the local regulations), to be contacted, and to contact the investigator during the study period.

inclusion criteria: * healthy people aged 3 years and above who have completed two or three doses of coronavac at least 3 months (≥ 90 days) before (3-8 weeks interval for the first and second dose of coronavac, and ≥3 months interval for the second and third dose); * participants (and/or their legal guardians for pediatric population) are able to understand and sign the informed consent voluntarily; * pregnancy and contraception: female participants of childbearing potential (post-menarche and pre-menopause that has not been undergone any sterilization surgery), who have a negative pregnancy test on the day of booster vaccination in the present study, has practiced adequate contraception or has abstained from all activities that could result in pregnancy for at least 28 days prior to the day of vaccination, and agree to continue adequate contraception through 3 months following the booster vaccination and are not currently breastfeeding; male participants of childbearing potential who agree to use adequate contraception through 3 months following the booster vaccination (and/or your female partner agree to use an acceptable method of birth control), which include refrain from donating sperm; note 1 :adequate contraception is defined as consistent and correct use of an approved contraceptive method in accordance with the product label. for example: * barrier method (such as condoms, diaphragm, or cervical cap) used in conjunction with spermicide * intrauterine device * prescription hormonal contraceptive taken or administered via oral (pill), transdermal (patch), subdermal, or im route * sterilization of a female participant's monogamous male partner prior to entry into the study note 2 : periodic abstinence (eg, calendar, ovulation, symptothermal, post-ovulation methods) and withdrawal are not acceptable methods of contraception. * participants are able to comply with study procedures based on the assessment of the investigator; * participants willing to provide verifiable identification (following the local regulations), to be contacted, and to contact the investigator during the study period.

inclusion criteria: healthy people aged 3 years and above who have completed two or three doses of coronavac at least 3 months (≥ 90 days) before (3-8 weeks interval for the first and second dose of coronavac, and ≥3 months interval for the second and third dose); participants (and/or their legal guardians for pediatric population) are able to understand and sign the informed consent voluntarily; pregnancy and contraception: female participants of childbearing potential (post-menarche and pre-menopause that has not been undergone any sterilization surgery), who have a negative pregnancy test on the day of booster vaccination in the present study, has practiced adequate contraception or has abstained from all activities that could result in pregnancy for at least 28 days prior to the day of vaccination, and agree to continue adequate contraception through 3 months following the booster vaccination and are not currently breastfeeding; male participants of childbearing potential who agree to use adequate contraception through 3 months following the booster vaccination (and/or your female partner agree to use an acceptable method of birth control), which include refrain from donating sperm; note 1 :adequate contraception is defined as consistent and correct use of an approved contraceptive method in accordance with the product label. for example: barrier method (such as condoms, diaphragm, or cervical cap) used in conjunction with spermicide intrauterine device prescription hormonal contraceptive taken or administered via oral (pill), transdermal (patch), subdermal, or im route sterilization of a female participant's monogamous male partner prior to entry into the study note 2 : periodic abstinence (eg, calendar, ovulation, symptothermal, post-ovulation methods) and withdrawal are not acceptable methods of contraception. participants are able to comply with study procedures based on the assessment of the investigator; participants willing to provide verifiable identification (following the local regulations), to be contacted, and to contact the investigator during the study period.

inclusion criteria: healthy people aged 3 years and above who have completed two or three doses of coronavac at least 3 months (≥ 90 days) before (3-8 weeks interval for the first and second dose of coronavac, and ≥3 months interval for the second and third dose); participants (and/or their legal guardians for pediatric population) are able to understand and sign the informed consent voluntarily; pregnancy and contraception: female participants of childbearing potential (post-menarche and pre-menopause that has not been undergone any sterilization surgery), who have a negative pregnancy test on the day of booster vaccination in the present study, has practiced adequate contraception or has abstained from all activities that could result in pregnancy for at least 28 days prior to the day of vaccination, and agree to continue adequate contraception through 3 months following the booster vaccination and are not currently breastfeeding; male participants of childbearing potential who agree to use adequate contraception through 3 months following the booster vaccination (and/or your female partner agree to use an acceptable method of birth control), which include refrain from donating sperm; note 1 :adequate contraception is defined as consistent and correct use of an approved contraceptive method in accordance with the product label. for example: barrier method (such as condoms, diaphragm, or cervical cap) used in conjunction with spermicide intrauterine device prescription hormonal contraceptive taken or administered via oral (pill), transdermal (patch), subdermal, or im route sterilization of a female participant's monogamous male partner prior to entry into the study note 2 : periodic abstinence (eg, calendar, ovulation, symptothermal, post-ovulation methods) and withdrawal are not acceptable methods of contraception. participants are able to comply with study procedures based on the assessment of the investigator; participants willing to provide verifiable identification (following the local regulations), to be contacted, and to contact the investigator during the study period.