Measles research suggests that vitamin A may reduce mortality rates, but it doesn’t prevent the disease or its spread. According to Harvard T.H. Chan School of Public Health associate professor Christopher Sudfeld, supplements won’t stop people from getting measles.
Sudfeld’s 2010 systematic review found that both vaccination and vitamin A treatment are effective interventions, but they work in different ways. Vitamin A is most beneficial in areas with high deficiency rates, like sub-Saharan Africa, where it can help reduce mortality. However, the effectiveness of supplemental vitamin A for non-deficient individuals remains unclear.
Sudfeld warned that excessive vitamin A intake can cause serious side effects, such as liver damage. He emphasized that vitamin A supplements should only be given under a doctor’s supervision. The most effective strategy for preventing measles is vaccination, Sudfeld said, citing the safety and efficacy of the measles, mumps, and rubella (MMR) vaccine.
Source: https://hsph.harvard.edu/news/vitamin-a-wont-prevent-measles-vaccination-will-says-expert