What is the mechanism by which Vitamin A (Retinol) helps treat measles infection?

From the Guidelines

Vitamin A plays a crucial role in treating measles infection by enhancing immune responses and maintaining epithelial tissue integrity, thereby reducing morbidity and mortality, particularly in populations with vitamin A deficiency. When administered to measles patients, vitamin A supports T-cell function, antibody production, and maintains the integrity of mucous membranes in the respiratory and gastrointestinal tracts, which are primary targets of measles virus infection 1. The recommended dosage is 200,000 IU for children 12 months and older, or 100,000 IU for infants less than 12 months, which should be repeated every 3 months as part of the routine vitamin A supplementation schedule 1.

• Key benefits of vitamin A supplementation in measles patients include:
  • Reduced severity and duration of measles infection
  • Prevention of complications like pneumonia and blindness
  • Enhanced immune function through regulation of gene expression by retinoic acid, the metabolite of vitamin A
  • Improved outcomes in populations with vitamin A deficiency, which is a common underlying condition that exacerbates measles symptoms and complications
• According to the recommendations, children with complicated measles should receive a second dose of vitamin A on day 2, highlighting the importance of prompt and adequate vitamin A supplementation in managing severe cases of measles 1.
• Overall, vitamin A supplementation is a critical component of measles treatment, particularly in areas where vitamin A deficiency is prevalent, and its benefits extend to reducing morbidity, mortality, and improving quality of life in affected individuals.

From the Research

Mechanism of Vitamin A in Treating Measles Infection

• The exact mechanism behind how Vitamin A helps to treat measles infection is not fully understood, but research suggests that it may be related to its immunomodulating properties 2.
• Vitamin A deficiency is associated with increased mortality and susceptibility to infection, particularly in children with measles 2, 3, 4, 5.
• Vitamin A supplementation has been shown to reduce mortality and complications resulting from measles, particularly when given in two doses of 200,000 IU on consecutive days 3, 4, 5, 6.
• The immune defect caused by vitamin A deficiency may be due to alterations in the glycoproteins of the lymphocyte membrane, an adverse effect on helper T-cell function, or the effect on epithelial tissue 2.

Effects of Vitamin A on Measles Infection

• Vitamin A therapy has been associated with a reduced risk of mortality in children under the age of two years, as well as a reduction in pneumonia-specific mortality 3, 4, 5, 6.
• Two doses of vitamin A (200,000 IU) on consecutive days have been shown to reduce the incidence of croup, but not pneumonia or diarrhea 3, 4.
• The effect of vitamin A on measles infection may be greater in children under the age of two years, and in areas with high case fatality 3, 4, 5.

Dosage and Formulation of Vitamin A

• The World Health Organization (WHO) recommends administration of an oral dose of 200,000 IU of vitamin A per day for two days to children with measles in areas where vitamin A deficiency may be present 3, 4, 5, 6.
• Two doses of water-based vitamin A have been associated with a greater reduction in mortality compared to oil-based preparations 3.
• The effectiveness of a single dose of vitamin A is unclear, and more research is needed to determine its effects 3, 4, 5, 6.