Surveillance data on influenza-like illness consultation rates in public General Outpatient Clinics (GOPC) and private general practitioners (GP), school absenteeism rates, and number of consultations with patients with febrile illness in Designated Flu Clinics which operated during the pandemic period; the inferred influenza level under the dynamic linear model based on the surveillance data streams and scaled to the range of the influenza activity proxy measure (product of laboratory influenza isolation rate and GP ILI rate); the inferred trend of influenza activity under the same model, scaled to the range [−1, 1]; the laboratory influenza detection rates from January 2004 through December 2009.

<p>The inferred influenza activity index was superimposed and color-coded from white (low) to red (high) in each panel. The vertical dashed line indicates the start of the pandemic period.