Figure 4

Number of influenza positive by type/subtype and by month of illness onset among hospitalized severe acute respiratory infection (SARI) patients and influenza like illness (ILI) outpatients in ten sentinel hospitals, China, Febuary 1, 2011 to October 27, 2013*. Panel A. Four Northern Hospitals. Panel B. Six Southern Hospitals. *The bars with diagonal slashes indicate isolates from ILI patients, while the solid bars indicate isolates from SARI patients.