inclusion criteria: a subject is eligible for inclusion in this study if all of the following criteria are met: 1. informed consent: the subject (or the subject's legally acceptable representative, if applicable) must be capable of giving written informed consent and, prior to the commencement of any study-specific procedure, must sign an icf indicating the consent on the subject's voluntary participation in the study and compliance with the requirements and restrictions listed on the icf. 2. vaccination status: the subject must have received homologous or heterologous vaccination with 3 doses of covid-19 inactivated and/or mrna vaccine(s) recognized by the local health authorities, with the last dose completed at least 90 days prior to imp vaccination. 3. gender and age: male or female, at the age of ≥ 18 and ≤ 80 on the day of signing the icf. 4. body weight and bmi: body weight ≥ 45 kg and bmi ≥ 18.5 kg/m2 and \< 30 kg/m2 at screening and baseline. 5. medical conditions or diagnoses: existence of all of the following medical conditions or diagnoses: 1. generally in good health with no clinically significant abnormality, as determined by medical history, physical examination, 12-lead ecg and clinical laboratory tests at screening and baseline; 2. normal vital signs at screening and baseline, as defined by: * body (tympanic) temperature ≤ 37.5°c; * resting pulse rate ≥ 50 and ≤ 100 bpm; and * dbp ≥ 50 and ≤ 90 mmhg and sbp ≥ 90 and ≤ 140 mmhg. 6. avoidance of pregnancy: willingness and agreement to undertake measures to confirm the subject's non-childbearing potential or avoid pregnancy of the subject or the subject's sexual partner(s) as detailed below: 1. a female subject who declares menopause must (i) confirm that she has not experienced a menstrual period for at least 12 consecutive months; and (ii) be willing to receive a fsh test to confirm her postmenopausal status; 2. a female subject who declares completion of surgical sterilization (e.g. hysterectomy, bilateral oophorectomy, bilateral tubal occlusion or ligation) must be able to provide valid medical evidence or permit access to the relevant medical records; 3. a female subject who is a woman of childbearing potential (wocbp) must be willing and agree to remain abstinent or practise at least one effective contraceptive method from at least 30 days prior to the day of imp vaccination and for 60 days after imp vaccination; 4. a male subject (i) who is sexually active with a wocbp (except who is permanently sterile by bilateral orchiectomy or vasectomy) must be willing and agree to remain abstinent or practise at least one effective contraceptive method from the day of imp vaccination and until 60 days after imp vaccination; and (ii) must be willing and agree to refrain from sperm donation during the aforesaid period. 7. breastfeeding: a female subject must be willing and agree to avoid engagement in breastfeeding at any time from the day of imp vaccination until 60 days after imp vaccination. 8. blood donation: willingness and agreement to avoid blood donation from screening to the end of the period of participation in this study.

inclusion criteria: a subject is eligible for inclusion in this study if all of the following criteria are met: 1. informed consent: the subject (or the subject's legally acceptable representative, if applicable) must be capable of giving written informed consent and, prior to the commencement of any study-specific procedure, must sign an icf indicating the consent on the subject's voluntary participation in the study and compliance with the requirements and restrictions listed on the icf. 2. vaccination status: the subject must have received homologous or heterologous vaccination with 3 doses of covid-19 inactivated and/or mrna vaccine(s) recognized by the local health authorities, with the last dose completed at least 90 days prior to imp vaccination. 3. gender and age: male or female, at the age of ≥ 18 and ≤ 80 on the day of signing the icf. 4. body weight and bmi: body weight ≥ 45 kg and bmi ≥ 18.5 kg/m2 and \< 30 kg/m2 at screening and baseline. 5. medical conditions or diagnoses: existence of all of the following medical conditions or diagnoses: 1. generally in good health with no clinically significant abnormality, as determined by medical history, physical examination, 12-lead ecg and clinical laboratory tests at screening and baseline; 2. normal vital signs at screening and baseline, as defined by: * body (tympanic) temperature ≤ 37.5°c; * resting pulse rate ≥ 50 and ≤ 100 bpm; and * dbp ≥ 50 and ≤ 90 mmhg and sbp ≥ 90 and ≤ 140 mmhg. 6. avoidance of pregnancy: willingness and agreement to undertake measures to confirm the subject's non-childbearing potential or avoid pregnancy of the subject or the subject's sexual partner(s) as detailed below: 1. a female subject who declares menopause must (i) confirm that she has not experienced a menstrual period for at least 12 consecutive months; and (ii) be willing to receive a fsh test to confirm her postmenopausal status; 2. a female subject who declares completion of surgical sterilization (e.g. hysterectomy, bilateral oophorectomy, bilateral tubal occlusion or ligation) must be able to provide valid medical evidence or permit access to the relevant medical records; 3. a female subject who is a woman of childbearing potential (wocbp) must be willing and agree to remain abstinent or practise at least one effective contraceptive method from at least 30 days prior to the day of imp vaccination and for 60 days after imp vaccination; 4. a male subject (i) who is sexually active with a wocbp (except who is permanently sterile by bilateral orchiectomy or vasectomy) must be willing and agree to remain abstinent or practise at least one effective contraceptive method from the day of imp vaccination and until 60 days after imp vaccination; and (ii) must be willing and agree to refrain from sperm donation during the aforesaid period. 7. breastfeeding: a female subject must be willing and agree to avoid engagement in breastfeeding at any time from the day of imp vaccination until 60 days after imp vaccination. 8. blood donation: willingness and agreement to avoid blood donation from screening to the end of the period of participation in this study.

inclusion criteria: a subject is eligible for inclusion in this study if all of the following criteria are met: informed consent: the subject (or the subject's legally acceptable representative, if applicable) must be capable of giving written informed consent and, prior to the commencement of any study-specific procedure, must sign an icf indicating the consent on the subject's voluntary participation in the study and compliance with the requirements and restrictions listed on the icf. vaccination status: the subject must have received homologous or heterologous vaccination with 3 doses of covid-19 inactivated and/or mrna vaccine(s) recognized by the local health authorities, with the last dose completed at least 90 days prior to imp vaccination. gender and age: male or female, at the age of ≥ 18 and ≤ 80 on the day of signing the icf. body weight and bmi: body weight ≥ 45 kg and bmi ≥ 18.5 kg/m2 and < 30 kg/m2 at screening and baseline. medical conditions or diagnoses: existence of all of the following medical conditions or diagnoses: generally in good health with no clinically significant abnormality, as determined by medical history, physical examination, 12-lead ecg and clinical laboratory tests at screening and baseline; normal vital signs at screening and baseline, as defined by: body (tympanic) temperature ≤ 37.5°c; resting pulse rate ≥ 50 and ≤ 100 bpm; and dbp ≥ 50 and ≤ 90 mmhg and sbp ≥ 90 and ≤ 140 mmhg. avoidance of pregnancy: willingness and agreement to undertake measures to confirm the subject's non-childbearing potential or avoid pregnancy of the subject or the subject's sexual partner(s) as detailed below: a female subject who declares menopause must (i) confirm that she has not experienced a menstrual period for at least 12 consecutive months; and (ii) be willing to receive a fsh test to confirm her postmenopausal status; a female subject who declares completion of surgical sterilization (e.g. hysterectomy, bilateral oophorectomy, bilateral tubal occlusion or ligation) must be able to provide valid medical evidence or permit access to the relevant medical records; a female subject who is a woman of childbearing potential (wocbp) must be willing and agree to remain abstinent or practise at least one effective contraceptive method from at least 30 days prior to the day of imp vaccination and for 60 days after imp vaccination; a male subject (i) who is sexually active with a wocbp (except who is permanently sterile by bilateral orchiectomy or vasectomy) must be willing and agree to remain abstinent or practise at least one effective contraceptive method from the day of imp vaccination and until 60 days after imp vaccination; and (ii) must be willing and agree to refrain from sperm donation during the aforesaid period. breastfeeding: a female subject must be willing and agree to avoid engagement in breastfeeding at any time from the day of imp vaccination until 60 days after imp vaccination. blood donation: willingness and agreement to avoid blood donation from screening to the end of the period of participation in this study.

inclusion criteria: a subject is eligible for inclusion in this study if all of the following criteria are met: informed consent: the subject (or the subject's legally acceptable representative, if applicable) must be capable of giving written informed consent and, prior to the commencement of any study-specific procedure, must sign an icf indicating the consent on the subject's voluntary participation in the study and compliance with the requirements and restrictions listed on the icf. vaccination status: the subject must have received homologous or heterologous vaccination with 3 doses of covid-19 inactivated and/or mrna vaccine(s) recognized by the local health authorities, with the last dose completed at least 90 days prior to imp vaccination. gender and age: male or female, at the age of ≥ 18 and ≤ 80 on the day of signing the icf. body weight and bmi: body weight ≥ 45 kg and bmi ≥ 18.5 kg/m2 and < 30 kg/m2 at screening and baseline. medical conditions or diagnoses: existence of all of the following medical conditions or diagnoses: generally in good health with no clinically significant abnormality, as determined by medical history, physical examination, 12-lead ecg and clinical laboratory tests at screening and baseline; normal vital signs at screening and baseline, as defined by: body (tympanic) temperature ≤ 37.5°c; resting pulse rate ≥ 50 and ≤ 100 bpm; and dbp ≥ 50 and ≤ 90 mmhg and sbp ≥ 90 and ≤ 140 mmhg. avoidance of pregnancy: willingness and agreement to undertake measures to confirm the subject's non-childbearing potential or avoid pregnancy of the subject or the subject's sexual partner(s) as detailed below: a female subject who declares menopause must (i) confirm that she has not experienced a menstrual period for at least 12 consecutive months; and (ii) be willing to receive a fsh test to confirm her postmenopausal status; a female subject who declares completion of surgical sterilization (e.g. hysterectomy, bilateral oophorectomy, bilateral tubal occlusion or ligation) must be able to provide valid medical evidence or permit access to the relevant medical records; a female subject who is a woman of childbearing potential (wocbp) must be willing and agree to remain abstinent or practise at least one effective contraceptive method from at least 30 days prior to the day of imp vaccination and for 60 days after imp vaccination; a male subject (i) who is sexually active with a wocbp (except who is permanently sterile by bilateral orchiectomy or vasectomy) must be willing and agree to remain abstinent or practise at least one effective contraceptive method from the day of imp vaccination and until 60 days after imp vaccination; and (ii) must be willing and agree to refrain from sperm donation during the aforesaid period. breastfeeding: a female subject must be willing and agree to avoid engagement in breastfeeding at any time from the day of imp vaccination until 60 days after imp vaccination. blood donation: willingness and agreement to avoid blood donation from screening to the end of the period of participation in this study.