Fig. 3.

Comparison of humoral responses of the patients with different ages in convalescence. A total of 326 samples was tested, they are divided into two age groups (< 65 yr and ≥ 65 yr). The titer levels of seven kinds of antibodies show a slight difference between the groups. Except for IgG and N-IgG, the titer trends of IgM, N-IgM, RBD-IgM, RBD-IgG and S1-total antibody are significantly different between the two age groups (P < 0.05). The trend line is fitted by LOESS and 95% confidence interval was shown in gray. The dashed line is the cutoff value. The inserted table summarizes the statistical data of the age group.