A nurse is collecting a medication history from the parent of a preschooler who comes to the clinic for routine immunizations. For which of the following findings should the nurse withhold the varicella immunization?

The correct answer is B: Receiving treatment for leukemia. This is because individuals with leukemia have weakened immune systems, making them more susceptible to infections. Administering a live vaccine like varicella could potentially cause severe complications in these individuals.
Incorrect choices:
A: A pregnant parent - Pregnancy is not a contraindication for varicella vaccine.
C: Taking acetaminophen for mild discomfort - Acetaminophen does not interfere with varicella vaccine.
D: An allergy to eggs - Varicella vaccine is made using gelatin, not eggs, so egg allergy is not a contraindication.