Department of Laboratory Medicine, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China.
Department of Medical Administration, Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, Chengdu, China.
Front Cell Infect Microbiol. 2020 Dec 22;10:558472. doi: 10.3389/fcimb.2020.558472. eCollection 2020.
SARS-CoV-2 nucleic acid testing (NAT) has been routinely used for COVID-19 diagnosis during this pandemic; however, there have been concerns about its high false negative rate. We dissected its detection efficiency with a large COVID-19 cohort study.
We analyzed SARS-CoV-2 NAT positive rates of 4,275 specimens from 532 COVID-19 patients in Sichuan Province with different disease severities, statuses, and stages, as well as different types and numbers of specimens.
The total positive rate of the 4,275 specimens was 37.5%. Among seven specimen types, BALF generated a 77.8% positive rate, followed by URT specimens (38.5%), sputum (39.8%), and feces/rectal swabs (34.1%). Specimens from critical cases generated a 43.4% positive rate, which was significantly higher than that of other severities. With specimens from patients at stable status, the SARS-CoV-2 positive rate was 40.6%, which was significantly higher than that of improved status (17.1%), but lower than that of aggravated status (61.5%). Notably, the positive rate of specimens from COVID-19 patients varied significantly from 85 to 95% during 3 days before and after symptom onset, to 20% at around 18 days after symptom onset. In addition, the detection rate increased from 72.1% after testing one throat swab, to 93.2% after testing three consecutive respiratory specimens from each patient.
SARS-CoV-2 NAT detection rates vary with patient disease severity and status, specimen type, number of specimens, and especially disease progression. Sampling as close to symptom onset as possible, and consecutively collecting more than one respiratory specimen could effectively improve SARS-CoV-2 NAT detection efficiency.
在本次大流行期间，SARS-CoV-2 核酸检测（NAT）已常规用于 COVID-19 的诊断；然而，人们一直担心其假阴性率较高。我们通过一项大型 COVID-19 队列研究来剖析其检测效率。
我们分析了来自四川省 532 名不同疾病严重程度、状态和阶段的 COVID-19 患者的 4275 份标本的 SARS-CoV-2 NAT 阳性率，以及不同类型和数量的标本。
4275 份标本的总阳性率为 37.5%。在七种标本类型中，BALF 的阳性率最高，为 77.8%，其次是 URT 标本（38.5%）、痰液（39.8%）和粪便/直肠拭子（34.1%）。重症病例标本的阳性率为 43.4%，明显高于其他严重程度的病例。在病情稳定的患者标本中，SARS-CoV-2 的阳性率为 40.6%，明显高于好转病例（17.1%），但低于恶化病例（61.5%）。值得注意的是，在症状出现前 3 天左右，COVID-19 患者标本的阳性率从 85%到 95%不等，而在症状出现后 18 天左右，阳性率降至 20%。此外，从每位患者连续检测三个呼吸道标本，每个标本各检测一次咽拭子，检测率从 72.1%提高到 93.2%。
SARS-CoV-2 NAT 检测率随患者疾病严重程度和状态、标本类型、标本数量，特别是疾病进展而变化。尽可能接近症状出现时采样，连续采集多个呼吸道标本可有效提高 SARS-CoV-2 NAT 检测效率。
