Grove Jurette S, Mayne Elizabeth S, Burgers Wendy A, Blackburn Jonathan, Jugwanth Sarika, Stevens Wendy, Scott Lesley, David Anura, Gededzha Maemu, Sanne Ian M, Maphayi Mpho R, Pillay Taryn, George Jaya A
Department of Chemical Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
National Health Laboratory Service, Johannesburg, South Africa.
S Afr J Infect Dis. 2021 Jul 26;36(1):286. doi: 10.4102/sajid.v36i1.286. eCollection 2021.
Serology testing is an important ancillary diagnostic to the reverse transcriptase polymerase chain reaction (RT-PCR) test for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We aimed to evaluate the performance of the Roche Elecsys™ chemiluminescent immunoassay (Rotkreuz, Switzerland), that detects antibodies against the SARS-CoV-2 nucleocapsid antigen, at an academic laboratory in South Africa.
Serum samples were collected from 312 donors with confirmed positive SARS-CoV-2 RT-PCR tests, with approval from a large university's human research ethics committee. Negative controls included samples stored prior to December 2019 and from patients who tested negative for SARS-CoV-2 on RT-PCR and were confirmed negative using multiple serology methods ( = 124). Samples were stored at -80 °C and analysed on a Roche cobas™ 602 autoanalyser.
Compared with RT-PCR, our evaluation revealed a specificity of 100% and overall sensitivity of 65.1%. The sensitivity in individuals > 14 days' post-diagnosis was 72.6%, with the highest sensitivity 31-50 days' post-diagnosis at 88.6%. Results were also compared with in-house serology tests that showed high agreement in majority of categories.
The sensitivity at all-time points post-diagnosis was lower than reported in other studies, but sensitivity in appropriate cohorts approached 90% with a high specificity. The lower sensitivity at earlier time points or in individuals without symptomatology may indicate failure to produce antibodies, which was further supported by the comparison against in-house serology tests.
血清学检测是严重急性呼吸综合征冠状病毒2（SARS-CoV-2）逆转录聚合酶链反应（RT-PCR）检测的重要辅助诊断方法。我们旨在评估罗氏Elecsys™化学发光免疫分析法（瑞士罗特kreuz）在南非一家学术实验室检测抗SARS-CoV-2核衣壳抗原抗体的性能。
在一所大型大学的人类研究伦理委员会批准下，从312名SARS-CoV-2 RT-PCR检测确诊为阳性的献血者中采集血清样本。阴性对照包括2019年12月之前储存的样本以及RT-PCR检测SARS-CoV-2呈阴性且使用多种血清学方法确认阴性的患者样本（n = 124）。样本储存在-80°C，并在罗氏cobas™ 602自动分析仪上进行分析。
与RT-PCR相比，我们的评估显示特异性为100%，总体敏感性为65.1%。诊断后>14天个体的敏感性为72.6%，诊断后31 - 50天敏感性最高，为88.6%。结果还与内部血清学检测进行了比较，在大多数类别中显示出高度一致性。
诊断后所有时间点的敏感性均低于其他研究报告，但在适当队列中的敏感性接近90%，特异性高。早期时间点或无症状个体的敏感性较低可能表明未能产生抗体，与内部血清学检测的比较进一步支持了这一点。
