HIV point-of-care (POC) testing may facilitate early infant diagnosis, but the accuracy of POC testing in the first week of life and in the setting of antiretroviral prophylaxis for the prevention of mother-to-child HIV transmission (MTCT) is unknown. This study aimed to evaluate the sensitivity and specificity of the Cepheid Xpert® HIV-1 Qual POC test compared with the Roche Taqman HIV DNA PCR platform to diagnose infant HIV infection in the first 96 hours of life.
As part of an early infant treatment study, infants < 96 hours of life were screened for HIV at 5 hospital maternity wards in Botswana. Infants received post-exposure antiretroviral prophylaxis (PEP) with single-dose nevirapine and zidovudine, and most mothers received 3-drug antiretroviral therapy in pregnancy and at delivery. Dried blot spot screening samples were initially tested using the Roche Taqman HIV DNA PCR platform. To evaluate sensitivity of POC testing, remaining dried blood spots from the PCR-positive screening samples were tested using the Cepheid Xpert® HIV-1 Qual test. Seventy-five HIV-exposed, PCR negative infants were also selected for testing by Cepheid to evaluate POC assay specificity. The study was powered to have a lower 95% confidence limit of 82% sensitivity with 15 true-positive samples.
Fourteen of 15 PCR positive samples tested positive by Cepheid POC, yielding a sensitivity of 93.3% (95% CI: 68.1 – 99.8%). Among the 15 PCR positive infants, baseline viral load ranged from <40 copies/ml to >10,000,000 copies/ml, with a median of 2,403 copies/ml (Table 1). Twelve (80%) of the 15 infants were exposed to maternal 3-drug antiretroviral therapy near delivery, and all but one received PEP prior to screening. The HIV RNA for the infant with false negative POC testing was 1661 copies/mL. Of note, two infants with low HIV RNA (< 40 copies/mL and 272 copies/ml) were correctly identified as HIV positive by Cepheid POC. All of the 75 PCR-negative samples tested negative by Cepheid POC, yielding a specificity of 100% (95% CI: 96.1 –100%).
Our study demonstrates high sensitivity and specificity for the Cepheid POC assay in the first week of life despite low median infant HIV RNA and extensive PEP. The Cepheid POC testing platform may be a useful approach for adding early infant HIV diagnosis in Botswana.