Summary of associations between clinical characteristics and viral single/co-infection or viral positive cases and viral negative cases.

Percentages were calculated based on the fraction of patients having a specific symptom within each group.aMedian (IQR) of age of each group.bfast breathing was defined according to the standard WHO [15].cMedian (IQR) of duration of hospitalization (days).dNumber and percentage of patients having duration of hospitalization lasted longer than 7 days.