inclusion criteria: 1. 18 ≤age ≤59 years; 2. vaccinated with two doses of sars-cov-2 vaccine (manufactured by sino biopharmaceutical limited or sinovac biotech co., ltd.) (≥6 months from the time of vaccination). 3. plan to vaccinate third dose vaccination (manufactured by sino biopharmaceutical limited or sinovac biotech co., ltd.); 4. voluntarily participate in the study with signed informed consent form.

inclusion criteria: 1. 18 ≤age ≤59 years; 2. vaccinated with two doses of sars-cov-2 vaccine (manufactured by sino biopharmaceutical limited or sinovac biotech co., ltd.) (≥6 months from the time of vaccination). 3. plan to vaccinate third dose vaccination (manufactured by sino biopharmaceutical limited or sinovac biotech co., ltd.); 4. voluntarily participate in the study with signed informed consent form.

inclusion criteria: 18 ≤age ≤59 years; vaccinated with two doses of sars-cov-2 vaccine (manufactured by sino biopharmaceutical limited or sinovac biotech co., ltd.) (≥6 months from the time of vaccination). plan to vaccinate third dose vaccination (manufactured by sino biopharmaceutical limited or sinovac biotech co., ltd.); voluntarily participate in the study with signed informed consent form.

inclusion criteria: 18 ≤age ≤59 years; vaccinated with two doses of sars-cov-2 vaccine (manufactured by sino biopharmaceutical limited or sinovac biotech co., ltd.) (≥6 months from the time of vaccination). plan to vaccinate third dose vaccination (manufactured by sino biopharmaceutical limited or sinovac biotech co., ltd.); voluntarily participate in the study with signed informed consent form.

inclusion criteria: 18 ≥age ≥59 years; vaccinated with two doses of sars-cov-2 vaccine (manufactured by sino biopharmaceutical limited or sinovac biotech co., ltd.) (≥6 months from the time of vaccination). plan to vaccinate third dose vaccination (manufactured by sino biopharmaceutical limited or sinovac biotech co., ltd.); voluntarily participate in the study with signed informed consent form.

inclusion criteria: 18 ≥age ≥59 years; vaccinated with two doses of sars-cov-2 vaccine (manufactured by sino biopharmaceutical limited or sinovac biotech co., ltd.) (≥6 months from the time of vaccination). plan to vaccinate third dose vaccination (manufactured by sino biopharmaceutical limited or sinovac biotech co., ltd.); voluntarily participate in the study with signed informed consent form.