Maternal HIV Viral Load Threshold for Guiding Extended Infant Prophylaxis

Objectives Infant postnatal prophylaxis (PNP) is universally recommended for all breastfed infants born from mothers living with HIV up to 6-weeks of age. Continuation of PNP was recommended for infants defined as at high-risk of HIV acquisition. We hypothesized that a single maternal viral load (mVL) at the end of the universal PNP period can accurately identify infants requiring extended prophylaxis. Methods We assessed 1398 VL of breastfeeding mothers from Zambia and Burkina Faso at baseline (week 6-8), months 6 and 12 post-partum. Infants were defined at high-risk of HIV acquisition when mVL was ≥ 1000 cp/mL. Results Mothers with a VL between 40 and 1000 cp/mL or ≥ 1000 cp/mL at baseline were 6 [95CI 3.7-9.6] or 18 [95CI 12.6-25.7] times more likely to have a VL above 1000 cp/mL during breastfeeding than mothers with a VL below 40 cp/mL. A 40 cp/mL threshold for mVL showed a better performance to identify infants eligible for extended PNP in comparison with the standard threshold. Conclusion A single mother VL at W6-8 enabled a sensitive identification of infants at risk of HIV acquisition throughout the breastfeeding period. This conclusion may pave the way for a simplified risk-stratified guideline for the initiation of extended infant PNP.