Pneumonia is a severe form of acute lower respiratory tract infection and is the leading cause of death among children under 5 years of age worldwide. Vitamin A deficiency is also a public health problem in many parts of the world, particularly Africa and South-East Asia. Vitamin A deficiency can cause visual impairment in the form of night blindness and may increase the risk of illness and death from childhood infections, including measles and those causing diarrhoea.
Vitamin A is essential to help combat infections in childhood and clinical trials have demonstrated that vitamin A supplementation reduces the severity of respiratory infections and mortality in children with measles. However results from studies in children without measles suggest that vitamin A has little protective effect except in children suffering from acute or chronic malnutrition, where some benefit of vitamin A supplementation has been observed.