Comparison of Epidemiological and Clinical Features of Childhood Influenza B by Season

Purpose: I did this study to know whether epidemiological and clinical features of influenza B were different by season. Methods: I collected the epidemiological informations of influenza B patients under 18 years old who had been admitted at the Department of Pediatrics, Yongin Severance Hospital from June 2017 to may 2018 (season A) and from June 2015 to May 2016 (season B). The infection was detected by rapid immunochromatographic assay for the influenza antigen. They were grouped, investigated and compared by season. Results: There were 14 cases in season A (group A) and 25 cases in season B (group B). Their mean age and male to female ratios were 60.9±48.5 months old and 11:3 for group A and 67.6±44.5 months old and 10:15 for group B. There was no significant difference for age between them (P =0.668), but for sex ratio (P =0.043). The most frequent month was January for group A and March for group B (P <0.001). Compared to group B, group A showed more prolonged fever after admission (1.3±1.1 day vs. 0.6±06 day, P =0.023), more frequent lethargy (71.4% vs. 0.0%, P <0.001), poor feeding (71.4% vs. 24.0%, P =0.004), vomiting (42.9% vs. 12.0%, P =0.048), and less rhinorrhea (42.9% vs. 80.0%, P =0.018), respectively. Group A showed more frequent abnormal laboratory findings than group B such as more severe lower serum CO2 content (