Infant prophylaxis.

a The substitution of stavudine occurred at a median age of 30 days (range, 8–40 days) b Zidovudine was administered for at least 6 weeks in all infants. c One infant also received 1 week of ritonavir. d Treatment prescribed prior to warnings from the Food and Drug Administration against use of ritonavir-boosted lopinavir in infants younger than age 14 days. e This infant received stavudine rather than zidovudine due to maternal receipt of stavudine antenatally. Infant prophylaxis.