Volume 15, Number 10—October 2009
Research
Review of an Influenza Surveillance System, Beijing, People’s Republic of China
Figure 5

Figure 5. Weekly influenza-like illness (ILI) rates by Early Aberration Reporting System to detect the onset of the influenza epidemic during the 2007–08 season, Beijing, People’s Republic of China. Squares and triangles represent different alert situations—C1-mild (C1), C2-medium (C2), and C3-ultra (C3)—automatically generated by the reporting system: diamond, C1C3; triangle, C2C3.