A. Mother to infant nAb transfer in the pre-ART cohort. Neutralizing antibody transfer was evaluated by a comparison of total medians of percent neutralization between mother and infant pairs on day of birth. Statistical significance was determined by non-parametric Mann-Whitney tests. B. Infant neutralization profile in the pre-ART cohort. Each infant sample was placed into one of three categories based on neutralization percentage compared to virus only samples: >90%, 90-70% or <70% which equates to highly neutralizing, mildly neutralizing, or non-neutralizing, respectively. (* P ≤ 0.05, ** P ≤ 0.01, *** P ≤ 0.001, **** P ≤ 0.0001)