inclusion criteria: 1. adults aged 18 years and over, including the elderly over 60 years and those with underlying diseases. 2. volunteers are able and willing to comply with the requirements of the clinical trial protocol and sign the informed consent form. 3. ≥ 4 months from the last sars-cov-2 infection (or never been infected), and 6 months or more from the first booster immunization of the covid-19 vaccine.

inclusion criteria: 1. adults aged 18 years and over, including the elderly over 60 years and those with underlying diseases. 2. volunteers are able and willing to comply with the requirements of the clinical trial protocol and sign the informed consent form. 3. ≥ 4 months from the last sars-cov-2 infection (or never been infected), and 6 months or more from the first booster immunization of the covid-19 vaccine.

inclusion criteria: adults aged 18 years and over, including the elderly over 60 years and those with underlying diseases. volunteers are able and willing to comply with the requirements of the clinical trial protocol and sign the informed consent form. ≥ 4 months from the last sars-cov-2 infection (or never been infected), and 6 months or more from the first booster immunization of the covid-19 vaccine.

inclusion criteria: adults aged 18 years and over, including the elderly over 60 years and those with underlying diseases. volunteers are able and willing to comply with the requirements of the clinical trial protocol and sign the informed consent form. ≥ 4 months from the last sars-cov-2 infection (or never been infected), and 6 months or more from the first booster immunization of the covid-19 vaccine.