Figure 4.

Hemagglutinin peptides targeted by pre-existing antibodies that predict the antibody response to the influenza vaccine. Pre-vaccine serum reactivity to HA peptides for each of the three strains was subjected to feature selection and prediction of the HAI response. The crossvalidated area under the ROC curve (cvAUROC) (A) and regression coefficients for each feature (B) from Model 1 were obtained from the cross-validation procedure. Excluding age from the learning procedure results in incorporation of adjacent peptide reactivities to Model 3 (C); however, the accuracy of the prediction drops to 0.711. Asterisks in (C) indicate significant age associations.