Soru

A $14$-day-old boy is brought to the clinic by his mother because his $4$-year-old sister was diagnosed with chickenpox yesterday. The sister's vesicular rash first appeared $48$ hours ago, and she has been isolated in her room since. The neonate was born at $39$ weeks gestation via uncomplicated vaginal delivery. The mother's prenatal laboratory screening was unremarkable, but she notes that she grew up in an isolated rural community and has never had chickenpox. Her prenatal varicella-zoster IgG antibody titer was negative. The neonate is exclusively breastfed. The mother also reports that the infant developed mild rhinorrhea and an occasional cough this morning. His rectal temperature is $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$), heart rate is $142/\text{min}$, and respiratory rate is $42/\text{min}$. Physical examination reveals an afebrile, alert infant in no acute distress. The lungs are clear to auscultation. Skin examination shows several scattered erythematous macules with 1- to 2-mm central yellow-white papules on the anterior chest and back. Which of the following is the most appropriate next step in management?