Department of Radiology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA.
Department of Pathology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA.
J Clin Microbiol. 2021 Aug 18;59(9):e0056921. doi: 10.1128/JCM.00569-21.
The urgent need for large-scale diagnostic testing for SARS-CoV-2 has prompted interest in sample collection methods of sufficient sensitivity to replace nasopharynx (NP) sampling. Nasal swab samples are an attractive alternative; however, previous studies have disagreed over how nasal sampling performs relative to NP sampling. Here, we compared nasal versus NP specimens collected by health care workers in a cohort of individuals clinically suspected of COVID-19 as well as SARS-CoV-2 reverse transcription (RT)-PCR-positive outpatients undergoing follow-up. We compared subjects being seen for initial evaluation versus follow-up, two different nasal swab collection protocols, and three different transport conditions, including traditional viral transport media (VTM) and dry swabs, on 307 total study participants. We compared categorical results and viral loads to those from standard NP swabs collected at the same time from the same patients. All testing was performed by RT-PCR on the Abbott SARS-CoV-2 RealTime emergency use authorization (EUA) (limit of detection [LoD], 100 copies viral genomic RNA/ml transport medium). We found low concordance overall, with Cohen's kappa (κ) of 0.49, with high concordance only for subjects with very high viral loads. We found medium concordance for testing at initial presentation (κ = 0.68) and very low concordance for follow-up testing (κ = 0.27). Finally, we show that previous reports of high concordance may have resulted from measurement using assays with sensitivity of ≥1,000 copies/ml. These findings suggest nasal-swab testing be used for situations in which viral load is expected to be high, as we demonstrate that nasal swab testing is likely to miss patients with low viral loads.
大规模诊断检测 SARS-CoV-2 的迫切需求促使人们对灵敏度足够高的样本采集方法产生了兴趣，以替代鼻咽（NP）采样。鼻拭子样本是一种很有吸引力的替代方法；然而，以前的研究对鼻采样相对于 NP 采样的表现存在分歧。在这里，我们比较了临床怀疑 COVID-19 的个体以及接受 SARS-CoV-2 逆转录（RT）-PCR 阳性门诊随访的个体中，由医护人员采集的鼻拭子与 NP 标本。我们比较了初次评估和随访的患者、两种不同的鼻拭子采集方案，以及三种不同的运输条件，包括传统的病毒运输介质（VTM）和干拭子，共纳入了 307 名研究参与者。我们比较了分类结果和病毒载量，以及与同一患者同时采集的标准 NP 拭子的结果。所有检测均通过 RT-PCR 对 Abbott SARS-CoV-2 RealTime 紧急使用授权（EUA）（检测限[LoD]为 100 拷贝病毒基因组 RNA/ml 运输介质）进行。我们发现总体一致性较低，Cohen's kappa（κ）为 0.49，仅在病毒载量非常高的患者中具有高度一致性。我们发现初次就诊时的检测具有中等一致性（κ=0.68），而随访检测的一致性非常低（κ=0.27）。最后，我们表明以前报告的高一致性可能是由于使用灵敏度≥1000 拷贝/ml 的检测方法进行测量导致的。这些发现表明，在预计病毒载量较高的情况下应使用鼻拭子检测，因为我们表明鼻拭子检测可能会漏诊病毒载量较低的患者。
