Infants were randomly allocated at less than 48 hours of age to: 6 weeks of zidovudine monotherapy; or 6 weeks of zidovudine with three doses of nevirapine in the first week of life; or 6 weeks of zidovudine, with nelfinavir and lamivudine for 2 weeks. Overall in this high-risk group the HIV transmission rate was 8.5%, and in multivariate analysis only ART arm and maternal viral load were significantly associated with transmission. For infants uninfected at birth, transmission was two-fold higher in the zidovudine-alone

arm compared to the multiple ART arms (P = 0.034). There was no significant difference in transmission rates between the two multiple ARV arms and neonatal neutropenia was significantly

higher in the three-drug arm. In a randomized African study, babies born to mothers presenting at delivery received single-dose nevirapine or single-dose nevirapine and 1 week of zidovudine. Of those HIV negative at Obeticholic Acid in vivo birth, 34 (7.7%) who received nevirapine plus zidovudine and 51 (12.1%) who received nevirapine alone were infected (P = 0.03): a protective efficacy of 36% for the dual combination [279]. However, in two other randomized African studies where the mothers received find more short-course ART, for infants uninfected at birth there was no significant difference in transmission rate at 6 weeks for dual versus monotherapy short-course regimens to the infant: zidovudine plus lamivudine versus nevirapine [280]; or zidovudine plus nevirapine versus nevirapine [281]. PEP for the infant of an untreated mother should be given as soon as possible after delivery. There are no studies of time of initiation of combination PEP, but in a US cohort study a significantly reduced risk of transmission was only observed in infants commenced on zidovudine when this was started within 48 hours of birth [158]. For this reason, infant

Carbohydrate PEP should only be started where a mother is found to be HIV positive after delivery if it is within 48–72 hours of birth. NSHPC data from the UK and Ireland 2001–2008 demonstrate how the clinical practice of combination PEP in neonates has increased over time [282]. In total, 99% of 8205 infants received any PEP, and for the 86% with data on type of PEP, 3% received dual and 11% triple. The use of triple PEP increased significantly over this period, from 43% to 71% for infants born to untreated women, and from 13% to 32% where mothers were viraemic despite cART. HIV infection status was known for 89% of infants with information on PEP; 14.7% of infants who received no PEP were infected (5 of 34, all born vaginally to untreated mothers), compared to 1% of those who received any PEP (72 of 7286). Among infants born vaginally to untreated mothers, those who received PEP were significantly less likely to be infected than those who did not (8.5% [4/47] vs. 45.5% [5/11], P = 0.002).