A 7-month-old boy is evaluated in the clinic for recurrent bacterial infections. His tonsils are not visible on physical examination. Serum immunoglobulin A (IgA) and IgG levels are markedly decreased, and serum IgM levels are slightly below normal. This infant should NOT be given the measles-mumps-rubella (MMR) vaccination because:

Question

Quizplus · Accepted Answer

The measles-mumps-rubella (MMR) preparation is a live, attenuated viral vaccine. The great advantage of this type of vaccine is that it elicits all the innate and adaptive immune responses that would naturally arise as a result of infection with the pathogenic viruses. As such, it is the ideal way of inducing protective immunity. Nevertheless, whereas the viruses in the vaccine have been manipulated in the laboratory to become nonpathogenic in individuals with intact immune systems, they can potentially cause disease in vulnerable patients, such as those with congenital immunodeficiencies. As such, administration of the MMR vaccine is contraindicated in an infant with X-linked severe combined immunodeficiency disease (SCID), because vaccination would place him at risk of developing fatal infection.

A 7-Month-Old Boy Is Evaluated in the Clinic for Recurrent