Assess population attributable fractions (PAFs) for late postnatal transmission (LPT) of human immunodeficiency virus-1 (HIV-1) in a cohort of HIV-1-exposed infants.
We used data established from a risk factor analysis of LPT (negative HIV-1 results through the 4-6 week visit, but positive assays thereafter through the 12-month visit) from a perinatal clinical trial conducted in three sub-Saharan countries. PAFs were calculated as the proportions of excess LPTs attributed to identified risk factors.
For the cohort of 1317 infants, 206 (15.6%) had only low maternal CD4+ counts (< 200 cells/mm3), 332 (25.2%) had only high maternal plasma viral loads (VLs) (> 50 000 copies/mL), and 81 (6.2%) had both low CD4+ counts and high VLs. Their PAFs were 26.0% [95% confidence interval (CI), 12.0%-36.0%], 37.0% (95% CI, 22.0%-51.0%) and 16.0% (95% CI, 6.0%-25.0%), respectively.
Our PAF analysis illustrates the public health impact of the substantial proportion of LPTs accounted for by high-risk women with both low CD4+ counts and high VLs. In light of these results, access to and use of antiretroviral therapy (ART) by high-risk HIV-1-infected pregnant women is essential. Additional strategies to reduce LPT for those not meeting criteria for ART should be implemented.
Keywords: Breast feeding, late postnatal transmission, prevention of mother to child transmission/vertical transmission, risk factors, viral load