Oral polio and rotavirus vaccines are significantly less effective in children living in the developing world. Tropical enteropathy, which is associated with intestinal inflammation, decreased absorption and increased permeability, may contribute substantially to oral vaccine failure in developing country settings. Other possible causes of oral vaccine underperformance include malnutrition, interference with maternal or breast milk antibodies, changes in gut microbiota, and genetic susceptibility.The primary Objective of this study is to determine whether decreased vaccine responsiveness to oral poliovirus or rotavirus vaccines is associated with the presence of tropical enteropathy.