An 18-month-old female toddler is evaluated in the pediatric infectious disease clinic for a routine health assessment. She was diagnosed with perinatally acquired human immunodeficiency virus (HIV) infection and was recently placed in foster care. The patient is currently receiving combination antiretroviral therapy. She has no history of opportunistic infections and appears active and well-nourished. Physical examination is unremarkable. Recent laboratory studies show an absolute CD4+ T-lymphocyte count of 450 cells/mm³ and a CD4 fraction of 12%. Her immunization records indicate she is missing several recommended doses. Which of the following immunizations must be strictly withheld from this patient at this time?
- Varicella vaccineAnswer
- BHepatitis A vaccine
- CPneumococcal conjugate vaccine
- DHaemophilus influenzae type b vaccine
- EInactivated poliovirus vaccine
Answer
The live-attenuated varicella vaccine must be strictly withheld because the patient has severe immunosuppression.
The correct answer is the varicella vaccine. This patient has perinatally acquired HIV with a CD4 fraction of 12%. In children aged 1 through 5 years, a CD4 fraction of less than 15% (or an absolute count of less than 500 cells/mm³) is the threshold that defines severe immunosuppression. Because severely immunocompromised patients have profound deficits in cell-mediated immunity, they are at high risk of developing severe, unchecked, and potentially fatal disseminated disease from the attenuated viruses used in live vaccines. Therefore, all live-attenuated vaccines—including varicella and measles-mumps-rubella (MMR)—must be strictly withheld until immune reconstitution is achieved via antiretroviral therapy (typically defined as a CD4 fraction of 15% or greater for at least 6 consecutive months).
Step-by-Step Solution
Key Concept
Administration of live-attenuated vaccines is contraindicated in pediatric patients with HIV who exhibit severe immunosuppression (CD4 percentage less than 15% in children aged 1 to 5 years).