Virologic and immunologic responses to antiretroviral treatment (ART) in infants may differ from older children due to immunologic, clinical, or epidemiologic characteristics.
Longitudinal ART responses were modeled and compared in HIV-infected infants and children enrolled in cohorts in Nairobi, Kenya. Participants were enrolled soon after HIV diagnosis, started on ART, and followed for 2 years. Viral load decline was compared between infant and child cohorts using a nonlinear mixed effects model and CD4% reconstitution using a linear mixed effects model.
Among 121 infants, median age at ART was 3.9 months; among 124 children, median age was 4.8 years. At baseline, viral load was higher among infants than children (6.47 vs. 5.91 log10 copies/ml, P < 0.001). Infants were less likely than children to suppress viral load to less than 250 copies/ml following 6 months of ART (32% infants vs. 73% children, P < 0.0001). CD4% was higher at baseline in infants than children (19 vs. 7.3%, P < 0.001). Older children had more rapid CD4% reconstitution than infants, but failed to catch up to infant CD4%. CONCLUSION
Despite substantially higher CD4% at ART initiation, viral suppression was significantly slower among infants than older children. New strategies are needed to optimize infant outcomes on ART.