inclusion criteria: 1. male or female aged ≥18 years when signing icf; 2. for cohort 1: participants who have not been vaccinated with any covid-19 vaccine; for cohort 2: participants who were fully vaccinated with 2 or 3 doses of inactivated covid-19 vaccine and the interval between the last dose of previously vaccination and the 1st study vaccination is 3 to 24 months; 3. healthy participants or participants with pre-existing medical conditions that are in stable condition. the "pre-existing medical conditions" include but not limited to hypertension, diabetes, chronic cholecystitis and cholelithiasis, chronic gastritis, etc. a stable medical condition is defined as disease not requiring significant change in therapy or hospitalization as a consequence of worsening disease state for at least 3 months prior to study participation; 4. the participant or his/her legal representative can sign written icf, and can fully understand the trial procedure, the risk of participating in the trial, and other interventions that are available if they do not participate in the trial; 5. the participant can read, understand, and fill in record cards by himself/herself or with help; 6. fertile men and women of childbearing potential voluntarily agree to take effective contraceptive measures from signing icf to 6 months after the last dose of study vaccination.

inclusion criteria: 1. male or female aged ≥18 years when signing icf; 2. for cohort 1: participants who have not been vaccinated with any covid-19 vaccine; for cohort 2: participants who were fully vaccinated with 2 or 3 doses of inactivated covid-19 vaccine and the interval between the last dose of previously vaccination and the 1st study vaccination is 3 to 24 months; 3. healthy participants or participants with pre-existing medical conditions that are in stable condition. the "pre-existing medical conditions" include but not limited to hypertension, diabetes, chronic cholecystitis and cholelithiasis, chronic gastritis, etc. a stable medical condition is defined as disease not requiring significant change in therapy or hospitalization as a consequence of worsening disease state for at least 3 months prior to study participation; 4. the participant or his/her legal representative can sign written icf, and can fully understand the trial procedure, the risk of participating in the trial, and other interventions that are available if they do not participate in the trial; 5. the participant can read, understand, and fill in record cards by himself/herself or with help; 6. fertile men and women of childbearing potential voluntarily agree to take effective contraceptive measures from signing icf to 6 months after the last dose of study vaccination.

inclusion criteria: male or female aged ≥18 years when signing icf; for cohort 1: participants who have not been vaccinated with any covid-19 vaccine; for cohort 2: participants who were fully vaccinated with 2 or 3 doses of inactivated covid-19 vaccine and the interval between the last dose of previously vaccination and the 1st study vaccination is 3 to 24 months; healthy participants or participants with pre-existing medical conditions that are in stable condition. the "pre-existing medical conditions" include but not limited to hypertension, diabetes, chronic cholecystitis and cholelithiasis, chronic gastritis, etc. a stable medical condition is defined as disease not requiring significant change in therapy or hospitalization as a consequence of worsening disease state for at least 3 months prior to study participation; the participant or his/her legal representative can sign written icf, and can fully understand the trial procedure, the risk of participating in the trial, and other interventions that are available if they do not participate in the trial; the participant can read, understand, and fill in record cards by himself/herself or with help; fertile men and women of childbearing potential voluntarily agree to take effective contraceptive measures from signing icf to 6 months after the last dose of study vaccination.

inclusion criteria: male or female aged ≥18 years when signing icf; for cohort 1: participants who have not been vaccinated with any covid-19 vaccine; for cohort 2: participants who were fully vaccinated with 2 or 3 doses of inactivated covid-19 vaccine and the interval between the last dose of previously vaccination and the 1st study vaccination is 3 to 24 months; healthy participants or participants with pre-existing medical conditions that are in stable condition. the "pre-existing medical conditions" include but not limited to hypertension, diabetes, chronic cholecystitis and cholelithiasis, chronic gastritis, etc. a stable medical condition is defined as disease not requiring significant change in therapy or hospitalization as a consequence of worsening disease state for at least 3 months prior to study participation; the participant or his/her legal representative can sign written icf, and can fully understand the trial procedure, the risk of participating in the trial, and other interventions that are available if they do not participate in the trial; the participant can read, understand, and fill in record cards by himself/herself or with help; fertile men and women of childbearing potential voluntarily agree to take effective contraceptive measures from signing icf to 6 months after the last dose of study vaccination.