A mother and her 2-week-old infant, who is breastfed, have been exposed to chicken pox. Although the mother had chicken pox as a child, she is concerned about her baby. The nurse explains:

The baby should receive immune globulin to protect him from the infection.

The infant is at risk because the baby has not been immunized against the disease.

Both infant and mother are at risk because the mother's immunity was acquired too long ago to be effective.

Neither are at risk, because the mother has naturally acquired immunity, and she passes antibodies to the baby through the breast milk.