To determine the optimal time for a second HIV-1 nucleic acid amplification assay to detect late postnatal transmission of HIV-1 (first negative test at 4–8 weeks of age) in resource limited settings.
A longitudinal analysis of data from HPTN 024
Children born to HIV-1 infected mothers enrolled in the HIV Prevention Trial Network trial 024 (HPTN 024) were tested for HIV-1 infection at six intervals within the first year of life. Mothers and infants received nevirapine prophylaxis. We estimated the probability of being alive and having a positive test in each interval after 4–8 weeks and at 30 days post-weaning, conditional on having acquired HIV during the late postnatal period. The interval with the highest probability was taken to be the optimal visit interval.
A total of 1609 infants from HPTN 024 had at least one HIV-1 diagnostic test and were included in the analysis. We found that testing at one month after weaning or 12 months of age (whichever comes first), identified 81% of those infected during the late postnatal period (after 4–8 weeks) through breastfeeding. In total, 93% (95% CI: 89,98) of all infected infants would be detected if tests were performed at these two time points.
In resource-limited settings, HIV-1 PCR testing at 4–8 weeks followed by a second test at one month after weaning or at one year of age (whichever comes first), led to the identification of the vast majority of HIV-1 infected infants.