We also found that sOP children have deficient production of serum antibodies to OMP CD, OppA, Hag, and PilA2 at asymptomatic Mcat NP colonization and onset of AOM (Ren et al., unpublished), similar to our findings for protein vaccine candidates of Spn (17) and NTHi (18). Here, MCAT is linked to infectious otitis media.