Inequitable coverage of vitamin A supplementation in Nigeria and implications for childhood blindness.

Background: Vitamin A deficiency (VAD) is of major public health significance; it is a risk factor for childhood deaths from diarrhoea and measles in low and middle-income countries and an important cause of preventable childhood blindness in low income countries. Vitamin A supplementation (VAS) is being implemented in many LMICs and high coverage reduces the prevalence of blinding corneal diseases in children. However, national estimates of coverage may not reveal any inequities in intra country coverage.