inclusion criteria: males or females aged ≥20 to <65 years old and have received adenovirus vector vaccine chadox1-ncov-19 (astra-zeneca) or sars-cov-2 messenger rna-1273 once within three months at least four weeks apart. the subject must sign the subject's inform consent, or the subject's legal representative must understand and agree, then sign inform consent according to procedure above. healthy or existing medical condition is stable, and within 3 months before being included in the trial, he or she has not been hospitalized due to illness, and his or her condition is expected to remain stable during the trial period.

inclusion criteria: males or females aged ≥20 to <65 years old and have received adenovirus vector vaccine chadox1-ncov-19 (astra-zeneca) or sars-cov-2 messenger rna-1273 once within three months at least four weeks apart. the subject must sign the subject's inform consent, or the subject's legal representative must understand and agree, then sign inform consent according to procedure above. healthy or existing medical condition is stable, and within 3 months before being included in the trial, he or she has not been hospitalized due to illness, and his or her condition is expected to remain stable during the trial period.

inclusion criteria: 1. males or females aged ≥20 to <65 years old and have received adenovirus vector vaccine chadox1-ncov-19 (astra-zeneca) or sars-cov-2 messenger rna-1273 once within three months at least four weeks apart. 2. the subject must sign the subject's inform consent, or the subject's legal representative must understand and agree, then sign inform consent according to procedure above. 3. healthy or existing medical condition is stable, and within 3 months before being included in the trial, he or she has not been hospitalized due to illness, and his or her condition is expected to remain stable during the trial period.

inclusion criteria: 1. males or females aged ≥20 to <65 years old and have received adenovirus vector vaccine chadox1-ncov-19 (astra-zeneca) or sars-cov-2 messenger rna-1273 once within three months at least four weeks apart. 2. the subject must sign the subject's inform consent, or the subject's legal representative must understand and agree, then sign inform consent according to procedure above. 3. healthy or existing medical condition is stable, and within 3 months before being included in the trial, he or she has not been hospitalized due to illness, and his or her condition is expected to remain stable during the trial period.