Methods The blood samples of individuals of different age and vocation in various counties of Qingyuan area were collected and the serum levels of SARS-CoV IgG antibody was tested by ELISA.

• 方法采集本地区各县区不同年龄、不同职业的人群血液,用酶联免疫法检测血清中SARS-CoV抗体IgG。