A 15-month-old boy is brought to the clinic for a health maintenance visit. At 12 months of age, he was hospitalized for 5 days due to a prolonged fever, bilateral nonexudative conjunctivitis, mucosal changes, and unilateral cervical lymphadenopathy. He was diagnosed with Kawasaki disease and received high-dose aspirin and intravenous immunoglobulin (IVIG). He has fully recovered, and his most recent echocardiogram was normal. His last immunizations were administered at age 6 months. His development is age-appropriate. His vital signs and physical examination today are within normal limits. Which of the following is the most appropriate immunization plan for this patient today?
- Administer DTaP, Hib, and PCV today; defer MMR and varicella vaccines until age 23 monthsAnswer
- BAdminister DTaP, Hib, PCV, MMR, and varicella vaccines today
- CAdminister MMR and varicella vaccines today; defer DTaP, Hib, and PCV until age 23 months
- DDefer all immunizations until age 23 months
- EAdminister DTaP, Hib, and PCV today; defer MMR and varicella vaccines until age 18 months
Answer
The most appropriate plan is to administer the inactivated vaccines (DTaP, Hib, and PCV) today and defer the live-attenuated vaccines (MMR and varicella) until the patient is 23 months of age.
The correct action is to administer the inactivated vaccines today while delaying the live vaccines until the patient reaches 23 months of age. This patient requires catch-up immunizations for those missed at his 12-month visit. Because he was treated with high-dose intravenous immunoglobulin (IVIG) for Kawasaki disease at 12 months of age, his immunization plan must be temporarily modified. IVIG contains a large pool of passively acquired IgG antibodies. These circulating antibodies will bind to and neutralize the weakened viruses present in live-attenuated vaccines (such as the measles, mumps, rubella [MMR] and varicella vaccines), resulting in an inadequate immune response. Therefore, live vaccines must be deferred until the exogenous antibodies have sufficiently degraded. The recommended delay depends on the dose of IVIG; for the high dose (2 g/kg) standardly used in Kawasaki disease, the delay is 11 months. Since he received IVIG at 12 months of age, he can safely receive his live vaccines at 23 months of age. Conversely, circulating antibodies do not significantly impair the immune response to inactivated vaccines or toxoids. Therefore, inactivated vaccines (such as DTaP, Hib, and PCV) should be administered today without delay to protect the child from these serious infections.
Step-by-Step Solution
Key Concept
High-dose intravenous immunoglobulin (IVIG) administration necessitates an 11-month delay for live-attenuated vaccines to prevent passive antibodies from neutralizing the vaccine virus. Inactivated vaccines can be administered on their normal schedule without delay.