Department of Immunology, OLGEN, Faculty of Medicine and Dentistry, Palacky University Olomouc and University Hospital Olomouc, Hnevotinska 3, 77900, Olomouc, Czech Republic.
Department of Microbiology, Faculty of Medicine and Dentistry, Palacky University Olomouc and University Hospital Olomouc, Olomouc, Czech Republic.
Virol J. 2021 May 4;18(1):95. doi: 10.1186/s12985-021-01567-3.
The early identification of asymptomatic yet infectious cases is vital to curb the 2019 coronavirus (COVID-19) pandemic and to control the disease in the post-pandemic era. In this paper, we propose a fast, inexpensive and high-throughput approach using painless nasal-swab self-collection followed by direct RT-qPCR for the sensitive PCR detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This approach was validated in a large prospective cohort study of 1038 subjects, analysed simultaneously using (1) nasopharyngeal swabs obtained with the assistance of healthcare personnel and analysed by classic two-step RT-qPCR on RNA isolates and (2) nasal swabs obtained by self-collection and analysed with direct RT-qPCR. Of these subjects, 28.6% tested positive for SARS-CoV-2 using nasopharyngeal swab sampling. Our direct RT-qPCR approach for self-collected nasal swabs performed well with results similar to those of the two-step RT-qPCR on RNA isolates, achieving 0.99 positive and 0.98 negative predictive values (cycle threshold [Ct] < 37). Our research also reports on grey-zone viraemia, including samples with near-cut-off Ct values (Ct ≥ 37). In all investigated subjects (n = 20) with grey-zone viraemia, the ultra-small viral load disappeared within hours or days with no symptoms. Overall, this study underscores the importance of painless nasal-swab self-collection and direct RT-qPCR for mass testing during the SARS-CoV-2 pandemic and in the post-pandemic era.
早期识别无症状但具有传染性的病例对于遏制 2019 年冠状病毒病（COVID-19）大流行和在后疫情时代控制该疾病至关重要。在本文中，我们提出了一种快速、廉价和高通量的方法，使用无痛鼻拭子自我采集，然后直接进行 RT-qPCR，以敏感地检测严重急性呼吸综合征冠状病毒 2（SARS-CoV-2）。该方法在一项针对 1038 例受试者的大型前瞻性队列研究中得到了验证，同时使用（1）医务人员协助采集的鼻咽拭子，并通过经典两步 RT-qPCR 对 RNA 分离物进行分析，（2）自我采集的鼻拭子并直接进行 RT-qPCR 进行分析。在这些受试者中，28.6%的人通过鼻咽拭子采样检测出 SARS-CoV-2 阳性。我们的直接 RT-qPCR 方法用于自我采集的鼻拭子，其结果与 RNA 分离物的两步 RT-qPCR 相似，阳性预测值和阴性预测值均为 0.99（Ct 值<37）。我们的研究还报告了灰色地带病毒血症，包括接近截止值 Ct 值（Ct≥37）的样本。在所有有灰色地带病毒血症的研究对象（n=20）中，超小病毒载量在数小时或数天内无症状消失。总的来说，这项研究强调了在 SARS-CoV-2 大流行期间和后疫情时代进行大规模检测时，无痛鼻拭子自我采集和直接 RT-qPCR 的重要性。
