Reevaluating immunization delays after red blood cell transfusion.

This is the first study of the impact of RBC transfusions on MMR vaccine immunogenicity. Although lower than in the literature (immunity rates, ≥90%), the results show a high rate of immunogenicity of the MMR vaccine in chronically transfused patients. Additionally, results suggest that MMR antibody content in transfusions will continue to decrease with time. Weighing the risks and benefits of disease prevention in a vulnerable population, a reevaluation of immunization delays after RBC transfusions is called for.