Aged over 18 years old In the volunteer’s vaccination history, the interval between the first and second dose is between 4 to 8 weeks and at least 3 months and at most 5 months have passed since the injection of the second dose of the volunteer's vaccination. The volunteer must be able and willing to cooperate with the researchers throughout the study period. The volunteer must be able to fully understand the executive processes of the study and to understand the explanations of the facilitators correctly. The volunteer would be able to understand the contents of the informed consent form and sign the informed consent before recruitment. Access to the medical records and test results if hospitalised for any reason including due to the suspected or confirmed COVID-19 should be allowed. The volunteer has been in a medically stable condition for the past three months (he/she has not been hospitalized, his / her chronic illness has not recurred). His / her chronic illness medication instructions have not changed due to lack of control over clinical symptoms, etc.)

Aged over 18 years old In the volunteer’s vaccination history, the interval between the first and second dose is between 4 to 8 weeks and at least 3 months and at most 5 months have passed since the injection of the second dose of the volunteer's vaccination. The volunteer must be able and willing to cooperate with the researchers throughout the study period. The volunteer must be able to fully understand the executive processes of the study and to understand the explanations of the facilitators correctly. The volunteer would be able to understand the contents of the informed consent form and sign the informed consent before recruitment. Access to the medical records and test results if hospitalised for any reason including due to the suspected or confirmed COVID-19 should be allowed. The volunteer has been in a medically stable condition for the past three months (he/she has not been hospitalized, his / her chronic illness has not recurred). His / her chronic illness medication instructions have not changed due to lack of control over clinical symptoms, etc.)