Correlations between IMS indicators for ILI and RSV activity vs traditional influenza surveillance datasets maintained by the CDC.

Correlation between IMS-ILI and CDC RSV laboratory-confirmed viral activity can be considered as a control comparison testing the specificity of IMS-ILI for influenza surveillance. Analyses performed at the national scale, 2003–04 to 2009–10. Values indicate Pearson correlation coefficients; values in bold are significant (P*Correlation for this control comparison is significantly weaker than for the other comparisons (P≤0.05), indicating that the IMS-ILI indicator is specific of weekly influenza activity while the IMS RSV indicator is specific of weekly RSV activity.