FIG 2.

Humoral immune responses in H7N9 survivors after recovery. (A to C) HI titers against H7N9 (A), H3N2 (B), and H1N1 (C) in eight individuals with elevated seasonal influenza virus antibody at the T1, T2, or T3 time points. Four patients had serial samples at T1, T2, and T3, and four patients had paired specimens at T1 and T2. (D to F) HI titers against H7N9 (A/Anhui/01/2013), H3N2 (A/Switzerland/9715293/2013), and H1N1 (A/California/04/2009) in the H7N9 survivors (n = 38). All eligible patients (categorized in Table 2), except for three patients who did not provide serum samples at T3, were analyzed. One patient provided samples at T1, 4 at T2, 8 at T3, 8 at T1 and T2, 11 at T2 and T3, and 2 at T1, T2, and T3. Generalized estimating equations (GEEs) were used to analyze all longitudinal data. (G to I) Patients were divided into groups by ICU admission (G), ARDS presentation (H), and ventilation status (I), and HI titers against H7N9 are shown. In the ICU admission group, one patient provided samples at T2, 2 at T3, 4 at T1 and T2, 3 at T2 and T3, and 1 at T1, T2, and T3; in patients without ICU admission, one patient provided samples at T1, 1 at T2, 4 at T3, 3 at T1 and T2, 6 at T2 and T3, and 1 at T1, T2, and T3 (G). In the ARDS group, three patients provided samples at T3, 7 at T1 and T2, and 1 at T1, T2, and T3; in patients without ARDS, one patient provided samples at T1, 1 at T2, 5 at T3, 1 at T1 and T2, 5 at T2 and T3, and 1 at T1, T2, and T3 (H). In the ventilation group, three patients provided samples at T3, 3 at T1 and T2, and 3 at T2 and T3; in patients without ventilation, one patient provided samples at T1, 1 at T2, 4 at T3, 5 at T1 and T2, 5 at T2 and T3, and 2 at T1, T2, and T3 (I). Generalized estimating equations (GEEs) were used to analyze longitudinal data in the same group across time points. The Mann-Whitney test was used for nonparametric comparisons between groups at each time point.