inclusion criteria: 1. male or female aged ≥12 years old when signing icf; 2. participants who were neither vaccinated with any covid-19 vaccine (including covid-19 vaccine or vaccine adjuvant in clinical trial) nor diagnosed with covid-19; 3. participants or his/her legal guardian (or entrusted person) can sign written icf and voluntarily participate in the trial, 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. participant him/herself or with the assistance of his/her family member is capable of finishing the 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 age voluntarily agree to take effective contraceptive measures from signing icf to 6 months after the last dose of study vaccination; the pregnancy test results of women of childbearing age are negative on screening.

inclusion criteria: 1. male or female aged ≥12 years old when signing icf; 2. participants who were neither vaccinated with any covid-19 vaccine (including covid-19 vaccine or vaccine adjuvant in clinical trial) nor diagnosed with covid-19; 3. participants or his/her legal guardian (or entrusted person) can sign written icf and voluntarily participate in the trial, 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. participant him/herself or with the assistance of his/her family member is capable of finishing the 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 age voluntarily agree to take effective contraceptive measures from signing icf to 6 months after the last dose of study vaccination; the pregnancy test results of women of childbearing age are negative on screening.

inclusion criteria: male or female aged ≥12 years old when signing icf; participants who were neither vaccinated with any covid-19 vaccine (including covid-19 vaccine or vaccine adjuvant in clinical trial) nor diagnosed with covid-19; participants or his/her legal guardian (or entrusted person) can sign written icf and voluntarily participate in the trial, 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; participant him/herself or with the assistance of his/her family member is capable of finishing the 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 age voluntarily agree to take effective contraceptive measures from signing icf to 6 months after the last dose of study vaccination; the pregnancy test results of women of childbearing age are negative on screening.

inclusion criteria: male or female aged ≥12 years old when signing icf; participants who were neither vaccinated with any covid-19 vaccine (including covid-19 vaccine or vaccine adjuvant in clinical trial) nor diagnosed with covid-19; participants or his/her legal guardian (or entrusted person) can sign written icf and voluntarily participate in the trial, 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; participant him/herself or with the assistance of his/her family member is capable of finishing the 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 age voluntarily agree to take effective contraceptive measures from signing icf to 6 months after the last dose of study vaccination; the pregnancy test results of women of childbearing age are negative on screening.