Fig. 3

Comparison of the decline rate in IgG antibody titer among the 219 subjects with positive total antibodies at baseline and three consecutive serum samples. A Comparison of the decline rate between underlying diseases and no underlying diseases. B A total of 65 people in the underlying disease group were positive for antibodies at baseline and in three consecutive samples. Comparison of the following three groups: hypertension group, hypertension combined with other diseases group, and other underlying diseases group. **P < 0.01; ***P < 0.001; ns: no significance