Infant HIV transmission despite maternal viral suppression: a case of post-weaning seroconversion

To the Editor-in-Chief, Despite widespread availability of antiretroviral therapy (ART) and comprehensive prevention of vertical transmission (PVT) programmes, rare cases of postnatal HIV transmission continue to occur. Maternal viral suppression during pregnancy and breastfeeding has dramatically reduced transmission risk, with global guidelines now recommending maternal ART as the cornerstone of prevention.1 Current evidence estimates the overall risk of pregnancy and postnatal HIV transmission to be less than 1% in mothers who are fully suppressed on ART.2 However, we report a case that illustrates a complex diagnostic and clinical challenge: infant HIV seroconversion following cessation of breastfeeding, despite sustained maternal virological suppression and adherence to all PVT interventions. The mother was a 19-year-old primigravida in Kampala, Uganda, diagnosed with HIV at 33 weeks gestation through routine antenatal screening. She was enrolled in the DolPHIN-2 study, a randomized controlled trial comparing dolutegravir-based versus efavirenz-based ART for late-presenting pregnant women (NCT03249181).3 On the day of diagnosis, she initiated standard ART consisting of tenofovir disoproxil fumarate, lamivudine and efavirenz (TDF/3TC/EFV). HIV-1 RNA was 106 539 copies/mL at baseline. Within 3 months of treatment initiation, she achieved plasma viral suppression (