Consistent with the hypothesis that the three-gene signature primarily reflects the host immune response to viruses, decision curve analysis showed that the signature offered the greatest net benefit (vs CRP and leukocyte count) to guide targeting of additional diagnostic tests, antiviral treatment, and infection control measures for proven or probable viral infections, whereas CRP offered the greatest net benefit for targeting of antibacterial treatment for proven or probable bacterial infections. The gene discussed is CRP; the disease is viral infectious disease.