A 4-year-old girl is brought by her mother to the pediatrician because of a rash. She had a fever and headache yesterday, and this morning broke out in a rash on her torso. The lesions are...

A 4-year-old girl is brought by her mother to the pediatrician because of a rash. She had a fever and headache yesterday, and this morning broke out in a rash on her torso. The lesions are erythematous macules and vesicles in different stages, distributed diffusely over her trunk but most prominent on her left upper chest and right fl ank. A diagnosis of chickenpox is made. Of note, there is a 16-year-old sibling in the household who has not been vaccinated and has never had chickenpox. Which of the following interventions will most successfully prevent infection of susceptible household contacts?

(A) Administration of intravenous acyclovir to the patient

(B) Administration of oral acyclovir to the patient and household contacts

(C) Administration of vaccine and intramuscular varicella zoster immunoglobulin to household contacts

(D) Administration of varicella vaccine to household contacts

(E) No prophylaxis is necessary for household contacts under age 25 years