Clinical characteristics and economic burden of influenza among children under 5 years old, in Suzhou, 2011-2017

Abstract

Objective: To understand the clinical characteristics and economic burden of influenza-like illness (ILI) children aged 0-59 months in the outpatient settings in Suzhou, China, 2011-2017. Methods: From March 2011 to February 2017, we conducted a prospective surveillance program on ILI for children aged less than 5 years at Soochow University Affiliated Children's Hospital. Through standard questionnaires and follow-up survey via telephone, we collected information regarding the demographic characteristics, medical history, clinical symptoms and both direct and indirect costs associated with influenza, of the patients. We then compared clinical characteristics and economic burden of influenza A/H1N1, A/H3N2, and B infections among children with ILI. Results: We enrolled 6 310 patients with ILI from March 2011 to February 2017 and collected all their throat swabs. 791 (12.9%) of the swabs showed positive for influenza virus, including 88 (11.1%) subtype influenza A/H1N1, 288 (36.4%) subtype influenza A/H3N2, and 415(52.5%) type influenza B. The proportions of cough, rhinorrhea, wheezing, vomiting and convulsion in influenza-positive children were higher than those influenza-negative children. Except for the prevalence rates of cough (χ(2)=9.227, P=0.010), wheezing (χ(2)=7.273, P=0.026) and vomiting (χ(2)=8.163, P=0.017), other clinical symptoms appeared similar between the three viral subtypes. Among all the ILI children, the average total cost per episode of influenza was 688.4 Yuan (95%CI: 630.1-746.7) for influenza-negative children; 768.0 Yuan (95%CI: 686.8-849.3) for influenza-positive children and 738.3 Yuan (95%CI: 655.5-821.1) for influenza B. Children with influenza A/H1N1 spent much more than those with influenza A/H3N2 or influenza B in the total cost (χ(2)=7.237, P=0.028). Conclusion: Children infected influenza showed higher prevalence rates of cough, rhinorrhea, wheezing, vomiting and convulsion than those without influenza. Influenza A/H1N1 subtype caused heavier economic burden than the other two influenza subtypes.