Undernutrition is a significant risk factor for disease and death in young children, making vaccination especially critical for this population.

Key Evidence: An analysis of the association between undernutrition and mortality in young children revealed that in 60% of deaths due to diarrhea, 52% of deaths due to pneumonia, 45% of deaths due to measles and 57% of deaths attributable to malaria, undernutrition was a contributing factor.

Key Evidence: The  presence of malnourishment correlates with the severity of cholera illness.  Additional factors include the number of V. cholerae bacteria ingested, lack of immunity from prior exposure or vaccination, pregnancy, lack of breast-feeding, immunocompromised state, reduced ability to produce gastric acid, and having blood group O.