We performed the process outlined above for severe acute respiratory syndrome (SARS), because its similarity to influenza presents the largest challenge of all of the diseases in GUAR-DIAN's current knowledge base. Even with this challenge, the area under the ROC curve was 0.929 and was optimized to 0.962 through hill-climbing. Gaussian decomposition showed good fidelity using 5 risk categories (Fig. 1) .