Browsing by Author "Hans, Lucia"

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    HIV Viral Load Testing in the South African Public Health Setting in the Context of Evolving ART Guidelines and Advances in Technology, 2013 - 2022
    (Multidisciplinary Digital Publishing Institute, 2023-08-22) Hans, Lucia; Cassim, Naseem; Sarang, Somayya; Hardie, Diana; Ndlovu, Silence; Venter, W.D. Francois; Da Silva, Pedro; Stevens, Wendy
    HIV viral load (VL) testing plays a key role in the clinical management of HIV as a marker of adherence and antiretroviral efficacy. To date, national and international antiretroviral treatment recommendations have evolved to endorse routine VL testing. South Africa (SA) has recommended routine VL testing since 2004. Progressively, the centralised HIV VL program managed by its National Health Laboratory Service (NHLS) has undergone expansive growth. Retrospective de-identified VL data from 2013 to 2022 were evaluated to review program performance. Test volumes increased from 1,961,720 performed in 2013 to 45,334,864 in 2022. The median total in-laboratory turnaround time (TAT) ranged from 94 h (2015) to 51 h (2022). Implementation of two new assays improved median TATs in all laboratories. Samples of VL greater than 1000 copies/mL declined steadily. Despite initial increases, samples of fewer than 50 copies/mL stagnated at about 70% from 2019 and declined to 68% in 2022. Some variations between assays were observed. Overall, the SA VL program is successful. The scale of the VL program, the largest of its kind in the world by some margin, provides lessons for future public health programs dependent on laboratories for patient outcome and program performance monitoring.
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    How South Africa Used National Cycle Threshold (Ct) Values to Continuously Monitor SARS-CoV-2 Laboratory Test Quality
    (Multidisciplinary Digital Publishing Institute, 2023-08-01) Scott, Lesley Erica; Hsiao, Nei-yuan; Dor, Graeme; Hans, Lucia; Marokane, Puleng; da Silva, Manuel Pedro; Preiser, Wolfgang; Vreede, Helena; Tsoka, Jonathan; Mlisana, Koleka; Stevens, Wendy Susan
    The high demand for SARS-CoV-2 tests but limited supply to South African laboratories early in the COVID-19 pandemic resulted in a heterogenous diagnostic footprint of open and closed molecular testing platforms being implemented. Ongoing monitoring of the performance of these multiple and varied systems required novel approaches, especially during the circulation of variants. The National Health Laboratory Service centrally collected cycle threshold (Ct) values from 1,497,669 test results reported from 6 commonly used PCR assays in 36 months, and visually monitored changes in their median Ct within a 28-day centered moving average for each assays’ gene targets. This continuous quality monitoring rapidly identified delayed hybridization of in the Allplex & trade; SARS-CoV-2 assay due to the Delta (B.1.617.2) variant; gene target failure in the TaqPath & trade; COVID-19 assay due to B.1.1.7 (Alpha) and the B.1.1.529 (Omicron); and recently gene delayed hybridization in the Xpress SARS-CoV-2 due to XBB.1.5. This near ;real-time; monitoring helped inform the need for sequencing and the importance of multiplex molecular nucleic acid amplification technology designs used in diagnostics for patient care. This continuous quality monitoring approach at the granularity of Ct values should be included in ongoing surveillance and with application to other disease use cases that rely on molecular diagnostics.
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    Laboratory investigation of low positive and discrepant HIV serology results
    (2014) Hans, Lucia; Korsman, Stephen; Hsiao, Marvin
    In our diagnostic virology laboratory, we test on average 1500 samples for HIV antibody/antigen each month, of which 0.6% produces problematic results. These problematic samples produce either weakly reactive screening and confirmatory results or, discrepant screening and confirmatory results. Both scenarios require additional tests to confirm HIV status thus increasing cost and turnaround time. There is a need to devise an optimal strategy within the laboratory to rapidly and easily manage these samples with minimal additional cost. The WHO recommends three HIV testing strategies. Strategy I ensures blood transfusion safety while strategies II and III are used for both surveillance and diagnostics in high prevalence and low prevalence areas respectively.1The 2010 National antenatal sentinel HIV & syphilis prevalence study reported the South African HIV prevalence as 30.2%.2 There were 1.8 million new cases of HIV infection in Sub-Saharan Africa in 2011.3South Africa (SA) is a high prevalence country and therefore the national HIV testing guideline is based on strategy II. The HIV screening and confirmatory strategy at Groote Schuur is based on these recommendations.