FIG 4 .

Disease severity measures in high- and low-NAI-titer groups. Symptom severity score (FLU-Pro participant self-assessment), number of symptoms, symptom duration, and shedding duration were evaluated for the participants in the groups with an NAI titer of ≥1:40 and <1:40. The median values (indicated by the bars) are shown as the first value above the bar. The interquartile ranges (indicated by the error bars) are shown in parentheses above the bars. The P values generated by the Wilcoxon rank sum test (two sided at 0.05 level) are indicated between the bars for the two NAI titer groups; P values that are statistically significant are indicated by an asterisk.