Data of the following will be collected:~Demographic data,including Name, Gender, Ethnic groups, ID Card number (age automatically calculated), Height/weight (automatic BMI calculation);~Previous disease/surgical history; 3. Previous COVID-19 infections; 4. COVID-19 vaccination history; 5. Infection after this screening; 6. Screening information for COVID-19 antibodies.~Atibody level against SARS-CoV-2 will be test.
About 15,000 to 25,000 subjects will be screened. Their information will be collected, venous blood will be sampled, their serum antibody levels will be detected, and the incidence of COVID-19 wil be followed up.