Fig. 1

Flow chart of the study design. Children with multiple or single ARTIs were selected from 4407 ARTI children during 2009–2015 as described in the Materials and Methods. For respiratory virome analysis, a total of 164 and 48 swabs from children with multiple and single ARTIs were included, respectively. For the immune profile determination, corresponding samples including 159 (5 sera without sufficient amount were excluded from cytokine assay) and 48 sera from children with multiple and single ARTIs, respectively, together with 20 non-ARTI healthy children were finally included