Tracking and predicting U.S. influenza activity with a real-time surveillance network
Fig 3
The estimated weighted ILI-related proportion of physician visits developed from the ITS Model 2 track well the actual weighted ILI-related proportion of physician visits as reported by the CDC.
ITS Model 2 estimates the CDC weighted ILI-related proportion of physician visits (ILIprop(ta)) by using a metric developed from ITS data (the total number of influenza test results divided by the total number of test machines, Vtotal(ta)), the weighted ILI-related proportion of physician visits as reported by the CDC with a 1-week lag (ILIprop(t(a−1))), and the ITS metric (the total number of influenza test results divided by the total number of test machines) with a 1-week lag (Vtotal(t(a−1))). Each graph shows two peaks with each peak relating to one flu season. The weighted ILI-related proportion of physician visits is along the y-axis. The CDC weighted ILI-related proportion of physician visits are in black, the ITS model estimates are in red, and the 95% prediction intervals are outlined by dark red dotted lines. The epidemiological week (epi week) is along the x-axis and spans from epi week 36 in 2015 to epi week 19 in 2017, except ITS data collection (and thus analysis) began later for Region 2 (epi week 13 in 2016 to epi week 19 in 2017) and Region 10 (epi week 2 in 2016 to epi week 19 in 2017). See Figure D in S1 Text for a visualization of raw data and estimates.