Vitamin A deficiency (VAD), a prevalent public health problem worldwide, and the correlation between vitamin A levels and childhood susceptibility are receiving increasing attention from pediatricians. In China, with the use of vitamin AD preparations, of which rural and remote areas are still the high prevalence of VAD. Vitamin A supplementation in preventive doses after birth is still necessary for newborns. Several studies at home and abroad have confirmed that VAD will increase the susceptibility of the organism to infectious diseases, induce the occurrence of inflammation and aggravate the symptoms of inflammation. At the same time, infectious diseases further affect the body’s absorption and utilization of vitamin A, leading to an increased degree of VAD. Studies have shown that vitamin A supplementation reduces the incidence and risk of death from diarrhea, measles, and respiratory infections in children. Immunomodulatory mechanisms of vitamin A Vitamin A plays an important role in maintaining the structural and functional integrity of epithelial cells. Vitamin A deficiency can lead to atrophy of epithelial cells, keratinization or cessation of mucus cell secretion, as well as an increase in lysosomes, which disrupts the integrity of skin and mucosa and reduces the body’s nonspecific immune function, thus causing a variety of infections. Nasal epithelial cells can secrete large amounts of retinoid dehydrogenase and binding receptors, an enzyme that metabolizes vitamin A to retinoic acid and promotes mucosal secretion of immunoglobulin A (IgA), while epithelial mucosal IgA is the first line of defense against pathogens entering the body. VAD and digestive tract infections VAD and diarrhea in children present a vicious cycle that vitamin A supplementation (VAS) helps to break. Vitamin A supplementation significantly reduces the incidence of digestive tract diseases such as diarrhea, and preventive vitamin A supplementation is recommended internationally for children at risk for VAD. VAD and respiratory infections The incidence of respiratory infections in children with VAD has been reported to be twice as high as normal children. Studies have shown that serum retinol levels decreased significantly in children with upper respiratory tract infections and combined wheezing compared to healthy children, and that serum retinol levels in children recovering from the condition were proportional to the reduction in airway resistance, suggesting that vitamin A aids in airway recovery after respiratory infections in children. The results of the study showed that each 10 μg/dl increase in serum retinol reduced the incidence of respiratory infections by 10% and reduced the overall prevalence by 6%. Since vitamin A cannot be synthesized in the body, inadequate dietary supply of vitamin A is a direct cause of VAD. Therefore, clinicians should provide timely information on childhood nutrition and dietary interventions to improve the intake of vitamin A in our children and correct VAD in a timely manner to reduce the occurrence of various infectious diseases.