Immunity and Vaccination Against Measles, Mumps, and Rubella in Adult Allogeneic Hematopoietic Stem Cell Transplant Recipients.

Large outbreaks of measles or rubella occasionally occur around the world, and measles infection can be severe and even fatal in transplant patients. However, limited data are available on immunity to measles, mumps, and rubella (MMR) in adult patients after allogeneic stem cell transplantation (allo-HCT). The aim of this study was to evaluate the immune status against MMR and the effects of vaccination against MMR in adult patients after allo-HCT. A total of 135 adult patients who were alive without relapse and new malignancy at 2 years after allo-HCT were included in this study. We measured IgG antibody to MMR before allo-HCT and annually thereafter. The probabilities of being seropositive to measles, mumps or rubella after allo-HCT were estimated according to the Kaplan-Meier method and compared among groups with the log-rank test. The probability of being seropositive at 2 years after allo-HCT in patients who were seropositive before allo-HCT was 60.6% for measles, 39.7% for mumps, and 52.2% for rubella. History of chronic graft-versus-host disease tended to be a risk factor for the loss of immunity against measles (hazard ratio [HR] 1.69, P = .064) and rubella (HR 1.75, P = .056). To predict the loss of immunity against MMR at 2 years after allo-HCT, we defined the following cutoff values for the IgG index before HCT: 18.2 for measles, 5.3 for mumps, and 21.4 for rubella using a receiver-operating characteristics curve. The lower-IgG groups experienced a significant loss of seropositivity at 2 years (39% versus 82% for measles, P < .001; 13% versus 59% for mumps, P < .001; and 33% versus 90% for rubella, P < .001). After this loss of immunity, 25 patients received a single vaccination against MMR. The seroconversion rates were 64%, 36%, and 72% for measles, mumps, and rubella, respectively. Loss of immunity to MMR commonly occurs in the first several years after transplantation. In the patients who lose the immunity, the seroconversion rate after 1 dose of MMR vaccine given at ≥2 years after transplantation is suboptimal.