Vitamin A deficiency is a major public health problem affecting an estimated 190 million preschool-age children, mostly from the World Health Organization (WHO) regions of Africa and South-East Asia (1). Infants and children have increased vitamin A requirements to promote rapid growth and to help combat infections. Inadequate intakes of vitamin A at this age could lead to vitamin A deficiency, which, when severe, may cause visual impairment (night blindness) or increase the risk of illness and mortality from childhood infections such as measles and those causing diarrhoea (2).
The combination of childhood underweight, micronutrient deficiencies (iron, vitamin A and zinc) and suboptimal breastfeeding is responsible for 7% of deaths and 10% of the total disease burden (3). Vitamin A deficiency alone is responsible for almost 6% of child deaths under the age of 5 years in Africa and 8% in South-East Asia (3). Vitamin A supplementation in children 6–59 months of age living in developing countries is associated with a reduced risk of all-cause mortality and a reduced incidence of diarrhoea (4). The mechanisms by which vitamin A reduces mortality are not fully understood, and it is not clear whether its action is mediated through the correction of underlying deficiencies or through adjuvant therapeutic effects. Vitamin A supplementation may improve gut integrity and therefore decrease the severity of some diarrhoeal episodes (5). The role of vitamin A in innate and adaptive immunity may also include reducing susceptibility to and/or severity of other infections (6, 7).
Many countries have integrated strategies to deliver vitamin A supplements to infants and children in their national health policies (8, 9). The delivery of vitamin A has been integrated into routine health services, for example through the establishment of biannual “special days”, when vitamin A supplementation is combined with other child survival interventions such as deworming or nutrition education. Vitamin A supplements are also commonly distributed as part of the Expanded Programme on Immunization (especially at 9 months, alongside measles vaccination). In 2009, about 77% of preschool children in more than 103 priority countries received two doses of vitamin A supplements (10).
Provision of high doses of vitamin A every 6 months until the age of 5 years was based on the principle that a single, large dose of vitamin A is well absorbed and stored in the liver, and then mobilized, as needed, over an extended period of time (11). A dose of 100 000 International Units (IU) in infants 6–11 months of age and 200 000 IU in children 12–59 months of age is considered to provide adequate protection for 4–6 months, with the exact interval depending on the vitamin A content of the diet and the rate of utilization by the body (8, 12).
In most children 6–59 months of age, a dose of 100 000–200 000 IU of vitamin A is well tolerated, although side-effects such as headache, nausea or vomiting, and diarrhoea have been reported in 3–7% of these children (13). However, these symptoms are transient, with the large majority starting and disappearing within 24 hours of dosing. There are no known deaths attributed solely to vitamin A toxicity due to overconsumption of vitamin A (13).
On a per-child basis, vitamin A supplementation is considered a low-cost intervention. Most of the vitamin A used during supplementation campaigns is supplied in gelatin capsules which cost approximately US$ 0.02 each (14), with an estimated cost of US$ 1–2 for delivery per child per year (15). The total cost of supplementation per death averted is estimated at US$ 200–250 (16, 17).
