What is the recommended time for a child with varicella to return to school?

A. A child with varicella (chickenpox) should return to school only after all the blisters have crusted over, indicating that the infectious stage has passed and they are no longer contagious. B. Receiving the varicella vaccine does not apply to children who already have the infection; vaccination is preventive, not a treatment for those already infected. C. Completing one week of antiviral medication is not a sufficient criterion for returning to school, as the child may still be contagious until all lesions are crusted. D. Returning to school as soon as the rash appears is not safe, as the child is highly contagious during the initial rash stage and until all lesions have crusted.