American Board of Internal Medicine (ABIM) Certification Practice Exam

What timing is recommended for administering MMR vaccination for patients who have had hematopoietic stem cell transplantation and no immune suppression?

1. 3 months post-transplant

2. 12 months post-transplant

3. 24 months post-transplant

4. 6 months post-transplant

The correct answer is: 24 months post-transplant

Administering the MMR (measles, mumps, rubella) vaccine in patients who have undergone hematopoietic stem cell transplantation is a critical consideration in ensuring effective immunization while minimizing the risk of complications. The recommended timing for vaccination is based on the patient's immune reconstitution status following transplantation. In general, it is advised to wait at least 24 months post-transplant before administering live attenuated vaccines like MMR. This waiting period allows sufficient time for the patient's immune system to recover adequately from the effects of the transplant and any preceding immunosuppressive therapy. By this time, the risk of vaccine-related complications is minimized, and the patient's immune response to the vaccine is more likely to be robust and effective. This two-year post-transplant period is particularly important for individuals who may still have residual immune suppression or altered immunity, which can occur even after leaving the acute recovery phase. Therefore, vaccinating too early, such as at 3, 6, or 12 months post-transplant, may not only put the patient at risk due to inadequate immune recovery but also might diminish the effectiveness of the vaccine. In summary, the recommendation to administer the MMR vaccine 24 months post-transplant is grounded in the