Recognising and managing increased HIV transmission risk in newborns

Prevention of mother-to-child transmission (PMTCT) programmes have improved maternal health outcomes and reduced the incidence of paediatric HIV, resulting in improved child health and survival. Nevertheless, high-risk vertical exposures remain common and are responsible for a high proportion of transmissions. In the absence of antiretrovirals (ARVs), an 8- to 12-hour labour has approximately the same 15% risk of transmission as 18 months of mixed feeding. The intensity of transmission risk is highest during labour and delivery; however, the brevity of this intra-partum period lends itself to post-exposure interventions to reduce such risk. There is good evidence that infant post-exposure prophylaxis (PEP) reduces intra-partum transmission even in the absence of maternal prophylaxis. Recent reports suggest that infant combination ARV prophylaxis (cARP) is more efficient at reducing intra-partum transmission than a single agent in situations of minimal pre-labour prophylaxis. Guidelines from the developed world have incorporated infant cARP for increased-risk scenarios. In contrast, recent guidelines for low-resource settings have rightfully focused on reducing postnatal transmission to preserve the benefits of breastfeeding, but have largely ignored the potential of augmented infant PEP for reducing intra-partum transmissions. Minimal pre-labour prophylaxis, poor adherence in the month prior to delivery, elevated maternal viral load at delivery, spontaneous preterm labour with prolonged rupture of membranes and chorioamnionitis are simple clinical criteria that identify increased intra-partum transmission risk. In these increased-risk scenarios, transmission frequency may be halved by combining nevirapine and zidovudine as a form of boosted infant PEP. This strategy may be important to reduce intra-partum transmissions when PMTCT is suboptimal.