 Repeat elements, short amino acid sequences repeated within a protein, were significantly enriched in antibody targets. Repeat elements were twofold higher in children living in the high versus moderate exposure setting. None such differences were observed for pectids without repeats, suggesting that antibody responses to repeat-containing regions may be more exposure dependent and all less durable in children than those without repeats. This article was authored by Mudra Rogovan, Katrina L. Calanta, Elias Duarte, and others.