Characteristics of enrolled influenza-like illness (ILI) cases, by medical setting and influenza virus status, n (%).

Note: aMunicipal district refers to seven central urban districts and suburban county refers to five county-level districts in Suzhou; bUnderlying medical conditions include asthma, chronic pulmonary disease, congenital heart disease, neuromuscular disease, renal dysfunction, blood disorders, immunosuppression, etc; cChi-square P<0.05 for comparison between ILI cases from outpatient clinics and ED; dChi-square P<0.05 for comparison between influenza positive and negative ILI cases.