Classifiers built on unstimulated and either Imiquimod- (AUC=0.8) or Poly(I:C)- (AUC=0.877) induced IFN genes could accurately stratify samples collected during acute illness compared to matched post-convalescent samples (symptom-free, 8.8 ± 2.5 weeks post-infection), independent of age (Figures 5B, S7G). Here, IFNA1 is linked to infection.