inclusion criteria: 1. age 18 and above. 2. obtain the subject's informed consent and sign the informed consent form. 3. the subject is able and willing to comply with the requirements of the clinical trial protocol and is willing and able to comply with all study plan contents and other requirements of the study. 4. armpit body temperature \< 37.3℃. 5. people who have had basic or enhanced immunization with covid-19 vaccine for 3 months or more; 6. sars-cov-2 nucleic acid screening was negative in the last 24 hours. 7. anti-sars-cov-2 igm antibody was negative during the screening period. 8. bmi of 18.5-30.0 kg/m2. 9. women's non-pregnancy period (pregnancy test results are negative), non-lactation period. 10. fertile women (wocbp) subjects had taken effective contraceptive measures 1 month before enrollment. 11. wocbp subjects and male subjects, who do not plan to become pregnant for 6 months from the screening period to the last dose of immunization, agree to take effective contraceptive measures for 6 months from the screening visit to the last dose of immunization. 12. wocbp subjects and male subjects agree not to donate eggs (oocytes, oocytes) for assisted reproduction (wocbp subjects) or to refrain from sperm donation (male subjects) for a period of 6 months from screening visit to the last dose of immunization. 13. subjects eligible for immunization with this product after medical history, physical examination and clinical judgment of health.

inclusion criteria: 1. age 18 and above. 2. obtain the subject's informed consent and sign the informed consent form. 3. the subject is able and willing to comply with the requirements of the clinical trial protocol and is willing and able to comply with all study plan contents and other requirements of the study. 4. armpit body temperature \< 37.3℃. 5. people who have had basic or enhanced immunization with covid-19 vaccine for 3 months or more; 6. sars-cov-2 nucleic acid screening was negative in the last 24 hours. 7. anti-sars-cov-2 igm antibody was negative during the screening period. 8. bmi of 18.5-30.0 kg/m2. 9. women's non-pregnancy period (pregnancy test results are negative), non-lactation period. 10. fertile women (wocbp) subjects had taken effective contraceptive measures 1 month before enrollment. 11. wocbp subjects and male subjects, who do not plan to become pregnant for 6 months from the screening period to the last dose of immunization, agree to take effective contraceptive measures for 6 months from the screening visit to the last dose of immunization. 12. wocbp subjects and male subjects agree not to donate eggs (oocytes, oocytes) for assisted reproduction (wocbp subjects) or to refrain from sperm donation (male subjects) for a period of 6 months from screening visit to the last dose of immunization. 13. subjects eligible for immunization with this product after medical history, physical examination and clinical judgment of health.

inclusion criteria: age 18 and above. obtain the subject's informed consent and sign the informed consent form. the subject is able and willing to comply with the requirements of the clinical trial protocol and is willing and able to comply with all study plan contents and other requirements of the study. armpit body temperature < 37.3℃. people who have had basic or enhanced immunization with covid-19 vaccine for 3 months or more; sars-cov-2 nucleic acid screening was negative in the last 24 hours. anti-sars-cov-2 igm antibody was negative during the screening period. bmi of 18.5-30.0 kg/m2. women's non-pregnancy period (pregnancy test results are negative), non-lactation period. fertile women (wocbp) subjects had taken effective contraceptive measures 1 month before enrollment. wocbp subjects and male subjects, who do not plan to become pregnant for 6 months from the screening period to the last dose of immunization, agree to take effective contraceptive measures for 6 months from the screening visit to the last dose of immunization. wocbp subjects and male subjects agree not to donate eggs (oocytes, oocytes) for assisted reproduction (wocbp subjects) or to refrain from sperm donation (male subjects) for a period of 6 months from screening visit to the last dose of immunization. subjects eligible for immunization with this product after medical history, physical examination and clinical judgment of health.

inclusion criteria: age 18 and above. obtain the subject's informed consent and sign the informed consent form. the subject is able and willing to comply with the requirements of the clinical trial protocol and is willing and able to comply with all study plan contents and other requirements of the study. armpit body temperature < 37.3℃. people who have had basic or enhanced immunization with covid-19 vaccine for 3 months or more; sars-cov-2 nucleic acid screening was negative in the last 24 hours. anti-sars-cov-2 igm antibody was negative during the screening period. bmi of 18.5-30.0 kg/m2. women's non-pregnancy period (pregnancy test results are negative), non-lactation period. fertile women (wocbp) subjects had taken effective contraceptive measures 1 month before enrollment. wocbp subjects and male subjects, who do not plan to become pregnant for 6 months from the screening period to the last dose of immunization, agree to take effective contraceptive measures for 6 months from the screening visit to the last dose of immunization. wocbp subjects and male subjects agree not to donate eggs (oocytes, oocytes) for assisted reproduction (wocbp subjects) or to refrain from sperm donation (male subjects) for a period of 6 months from screening visit to the last dose of immunization. subjects eligible for immunization with this product after medical history, physical examination and clinical judgment of health.