What is your approach to a patient with undetectable MMR titers checked prior to or during immunosuppression and a history of MMR vaccination in childhood?

MMR titers are good correlates of protection.

If any titer is undetectable it could be one of these situations:

• Primary failure. The components of the MMR have different efficacy. Two doses of appropriately given MMR will have 96+% against measles, but only 88% for mumps. Thus 1 in 10 appropriately...