Figure 4
From: Rapid detection of pandemic influenza in the presence of seasonal influenza
Detection of a pandemic by the WCR method. Probability values of weekly (WCR, NHB) pairs for the model pandemic cases are obtained from the distribution shown in Figure 2. Two examples, one each for pandemic starting weeks 1 (top) and 15 (bottom), are for a single run of the pandemic model. Pandemic cases were sampled at the reporting rate of 0.5% from the weekly infections and added to the 2004-05 seasonal data and WCR and NHB were calculated from the resultant time series. The dashed lines represent the two values of the detection threshold δ: 0.000059 (Sp = 99%) and 0.0008 (Sp = 95%). The pandemic starting on week 1 was detected on week 7, while the one starting on week 15 was detected on week 21.