inclusion criteria: 1. male or female aged ≥18 years old when signing icf; 2. for cohort 1: participants who were fully vaccinated with 2 doses of inactivated covid-19 vaccine (sinopharm inactivated covid-19 vaccine) or previously diagnosed with covid-19. the interval between the last dose and this study vaccination is ≥3 months and ≤12 months. the interval between the last day diagnosed with covid-19 and this study vaccination is ≥3 months and ≤12 months; for cohort 2: participants who were fully vaccinated with 2 doses of mrna covid-19 vaccine (comirnaty from pfizer or mrna-1273 from moderna) or previously diagnosed with covid-19. the interval between the last dose and this study vaccination is ≥3 months and ≤12 months. the interval between the last day diagnosed with covid-19 and this study vaccination is ≥3 months and ≤12 months; 3. the participant can sign the written icf (by applying his / her signature or fingerprint "for illiterate subject"), and can fully understand the trial procedure, the risk of participating in the trial, and other interventions that can be selected if they do not participate in the trial; 4. the participant and/or his entrusted person has the ability to read, understand, and fill in record cards; 5. healthy participants or participants with pre-existing medical conditions who are in stable condition. the "pre-existing medical conditions" include but not limited to hypertension, diabetes, chronic cholecystitis and cholelithiasis, chronic gastritis that meet the described criteria. a stable medical condition is defined as disease not requiring significant change in therapy or no need for hospitalization as a consequence of worsening disease state for at least 3 months prior to enrollment; 6. fertile men and women of childbearing potential voluntarily agree to take effective contraceptive measures from signing icf to 6 months after the study vaccination; the pregnancy test results of women of childbearing potential are negative on screening.

inclusion criteria: 1. male or female aged ≥18 years old when signing icf; 2. for cohort 1: participants who were fully vaccinated with 2 doses of inactivated covid-19 vaccine (sinopharm inactivated covid-19 vaccine) or previously diagnosed with covid-19. the interval between the last dose and this study vaccination is ≥3 months and ≤12 months. the interval between the last day diagnosed with covid-19 and this study vaccination is ≥3 months and ≤12 months; for cohort 2: participants who were fully vaccinated with 2 doses of mrna covid-19 vaccine (comirnaty from pfizer or mrna-1273 from moderna) or previously diagnosed with covid-19. the interval between the last dose and this study vaccination is ≥3 months and ≤12 months. the interval between the last day diagnosed with covid-19 and this study vaccination is ≥3 months and ≤12 months; 3. the participant can sign the written icf (by applying his / her signature or fingerprint "for illiterate subject"), and can fully understand the trial procedure, the risk of participating in the trial, and other interventions that can be selected if they do not participate in the trial; 4. the participant and/or his entrusted person has the ability to read, understand, and fill in record cards; 5. healthy participants or participants with pre-existing medical conditions who are in stable condition. the "pre-existing medical conditions" include but not limited to hypertension, diabetes, chronic cholecystitis and cholelithiasis, chronic gastritis that meet the described criteria. a stable medical condition is defined as disease not requiring significant change in therapy or no need for hospitalization as a consequence of worsening disease state for at least 3 months prior to enrollment; 6. fertile men and women of childbearing potential voluntarily agree to take effective contraceptive measures from signing icf to 6 months after the study vaccination; the pregnancy test results of women of childbearing potential are negative on screening.

inclusion criteria: male or female aged ≥18 years old when signing icf; for cohort 1: participants who were fully vaccinated with 2 doses of inactivated covid-19 vaccine (sinopharm inactivated covid-19 vaccine) or previously diagnosed with covid-19. the interval between the last dose and this study vaccination is ≥3 months and ≤12 months. the interval between the last day diagnosed with covid-19 and this study vaccination is ≥3 months and ≤12 months; for cohort 2: participants who were fully vaccinated with 2 doses of mrna covid-19 vaccine (comirnaty from pfizer or mrna-1273 from moderna) or previously diagnosed with covid-19. the interval between the last dose and this study vaccination is ≥3 months and ≤12 months. the interval between the last day diagnosed with covid-19 and this study vaccination is ≥3 months and ≤12 months; the participant can sign the written icf (by applying his / her signature or fingerprint "for illiterate subject"), and can fully understand the trial procedure, the risk of participating in the trial, and other interventions that can be selected if they do not participate in the trial; the participant and/or his entrusted person has the ability to read, understand, and fill in record cards; healthy participants or participants with pre-existing medical conditions who are in stable condition. the "pre-existing medical conditions" include but not limited to hypertension, diabetes, chronic cholecystitis and cholelithiasis, chronic gastritis that meet the described criteria. a stable medical condition is defined as disease not requiring significant change in therapy or no need for hospitalization as a consequence of worsening disease state for at least 3 months prior to enrollment; fertile men and women of childbearing potential voluntarily agree to take effective contraceptive measures from signing icf to 6 months after the study vaccination; the pregnancy test results of women of childbearing potential are negative on screening.

inclusion criteria: male or female aged ≥18 years old when signing icf; for cohort 1: participants who were fully vaccinated with 2 doses of inactivated covid-19 vaccine (sinopharm inactivated covid-19 vaccine) or previously diagnosed with covid-19. the interval between the last dose and this study vaccination is ≥3 months and ≤12 months. the interval between the last day diagnosed with covid-19 and this study vaccination is ≥3 months and ≤12 months; for cohort 2: participants who were fully vaccinated with 2 doses of mrna covid-19 vaccine (comirnaty from pfizer or mrna-1273 from moderna) or previously diagnosed with covid-19. the interval between the last dose and this study vaccination is ≥3 months and ≤12 months. the interval between the last day diagnosed with covid-19 and this study vaccination is ≥3 months and ≤12 months; the participant can sign the written icf (by applying his / her signature or fingerprint "for illiterate subject"), and can fully understand the trial procedure, the risk of participating in the trial, and other interventions that can be selected if they do not participate in the trial; the participant and/or his entrusted person has the ability to read, understand, and fill in record cards; healthy participants or participants with pre-existing medical conditions who are in stable condition. the "pre-existing medical conditions" include but not limited to hypertension, diabetes, chronic cholecystitis and cholelithiasis, chronic gastritis that meet the described criteria. a stable medical condition is defined as disease not requiring significant change in therapy or no need for hospitalization as a consequence of worsening disease state for at least 3 months prior to enrollment; fertile men and women of childbearing potential voluntarily agree to take effective contraceptive measures from signing icf to 6 months after the study vaccination; the pregnancy test results of women of childbearing potential are negative on screening.