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Difficulty: MediumImmunizations and Vaccine-Preventable Diseases

A 5-year-old boy is brought to the pediatric oncology clinic by his parents for a scheduled health maintenance visit in mid-October. The child was diagnosed with standard-risk acute lymphoblastic leukemia two years ago and is presently receiving maintenance chemotherapy consisting of daily oral 6-mercaptopurine and weekly oral methotrexate. He has had no recent fevers, chills, sick contacts, or systemic symptoms. Vital signs are within normal limits, and physical examination shows no abnormalities. A review of his immunization record reveals that he received all standard childhood vaccines up to age 2, but he has not yet received any of the routine immunizations typically administered between 4 and 6 years of age. Which of the following vaccines is absolutely contraindicated for this patient at this time?

  1. Varicella virus vaccineAnswer
  2. B
    Inactivated poliovirus vaccine
  3. C
    Diphtheria, tetanus, and acellular pertussis vaccine
  4. D
    Quadrivalent inactivated influenza vaccine
  5. E
    Haemophilus influenzae type b vaccine

Answer

The varicella virus vaccine is contraindicated because it is a live-attenuated vaccine, which poses a severe risk to an immunocompromised patient on active chemotherapy.
The correct answer is the varicella virus vaccine. This pediatric patient is currently receiving maintenance chemotherapy (6-mercaptopurine and methotrexate) for acute lymphoblastic leukemia. These medications cause significant immunosuppression by inhibiting cellular division and immune cell proliferation. According to general immunization guidelines, live-attenuated vaccines (such as varicella, MMR, rotavirus, and the intranasal live-attenuated influenza vaccine) are strictly contraindicated in severely immunocompromised patients. The administration of a live-attenuated vaccine in this setting can lead to uncontrolled viral replication and severe, potentially fatal, disseminated vaccine-strain infection.

Step-by-Step Solution

1
Determine the patient's current immune status based on the clinical history.
The patient is receiving daily 6-mercaptopurine and weekly methotrexate for acute lymphoblastic leukemia, making him severely immunocompromised.
Establishing the immune status is the critical first step in determining vaccine safety and contraindications.
2
Recall the general rule for immunizing immunocompromised patients.
Inactivated, killed, and toxoid vaccines are generally safe to administer, whereas live-attenuated vaccines are strictly contraindicated.
Live-attenuated vaccines contain weakened pathogens that can cause severe, uninhibited, and disseminated infections in patients lacking adequate cell-mediated immunity.
3
Classify the provided vaccine options into live-attenuated versus inactivated types.
Varicella is a live-attenuated vaccine. Inactivated poliovirus, DTaP, inactivated influenza, and Hib are all non-replicating/inactivated vaccines.
Identifying the vaccine type allows the application of the contraindication rule.
4
Select the vaccine that matches the contraindication criteria.
The varicella virus vaccine is chosen as the absolutely contraindicated immunization.
It is the only live-attenuated vaccine among the options provided.

Key Concept

Live-attenuated vaccines are absolutely contraindicated in severely immunocompromised patients, including those undergoing active chemotherapy, due to the risk of severe vaccine-strain infection.
Estimated Time:1m 15s
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Immunizations and Vaccine-Preventable Diseases

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