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      Nucleic acid detection analysis of 71 cases of COVID-19 with biological samples of diferent disease course

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          Objective To study the nucleic acid detection results of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) in different biological samples of COVID-19 (coronavirus disease 2019, COVID-19) patients in different stages, and we analyze the results and clinical significance.

          Methods The clinical data of patients diagnosed with COVID-19 in Qishan Hospital of Yantai City from January 24 to February 28 were collected by cross-sectional observation design. Real­time reverse transcriptase polymerase chain reaction (RT-PCR) was used to detect SARS-CoV-2 nucleic acid in pharyngeal swabs and sputum samples at different stages of the disease. The negative conversion time of nucleic acid in severe and ordinary patients was statistically analyzed.

          Results A total of 71 patients were included, including 40 males and 31 females. 80.3% of the patients had fever as the first symptom, and cough accounted for 57.8%. There were 57 common cases, accounting for 80.3%, 5 mild cases, accounting for 7.0%, 8 severe cases, accounting for 11.3%, and 1 critical case, accounting for 1.4%. 40 cases were discharged with an average hospital stay of (22.78±6.19) days. The nucleic acid detection rates of nasopharyngeal swab samples in the 1st, 2nd, 3rd, 4th and 5th weeks of the disease were 100.0%, 48.6%, 44.7%, 19.1% and 11.5%; the nucleic acid detection rates of sputum samples in the 1st, 2nd, 3rd, 4th and 5th weeks were 87.5%, 88.2%, 86.1%, 58.7% and 33.3%; The false negative rates of pharyngeal swabs in the 1st, 2nd, 3rd, 4th and 5th weeks were 12.5%, 52.9%, 44.1%, 42.9% and 20.0%, respectively. In the same period, the coincidence rate of the results of the two kinds of samples was higher in the first week and the fifth week of the disease. There was no case of negative detection of virological nucleic acid in the first week of the disease. In the second week of the disease, 2 patients turned negative for virological nucleic acid test, accounting for 3.9%. In the 3rd week, 12 cases were negative, accounting for 23.5%. At the 4th week, nucleic acid test turned negative in 20 cases (39.2%). In the fifth week, the virus nucleic acid turned negative in 16 cases, accounting for 31.4%. After 5 weeks, the virus nucleic acid turned negative in 1 case, accounting for 2.0%. The negative conversion rate of viral nucleic acid was the highest in the 4th and 5th week, reaching 70.6%. The negative conversion time (30.00±3.54) days of nucleic acid in patients with critical (severe) type was longer than that in patients with common nucleic acid (24.00±5.84) days, and there was significant difference between the two groups ( P<0.05).

          Conclusion The main symptoms of COVID-19 are fever, dry cough, fatigue, muscle soreness, chills and shiver. Most of the cases were common cases.The positive rate of nucleic acid detection in sputum samples was higher than that in nasopharyngeal swabs.Some of nasopharyngeal swab test results are false negative, and the combination of the two samples can reduce the occurrence of false negative.The negative conversion rate of viral nucleic acid was the highest in the 4th and 5th week of the disease.The persistence of virus in critically ill patients may be one of the main factors for the aggravation of the disease.


          摘要:目的 对新型冠状病毒肺炎(coronavirus disease 2019, COVID-19)患者在不同病程阶段不同生物学样本新型 冠状病毒(SARS-CoV-2)进行核酸检测,并分析其临床意义。 方法 采用横断面观察性研究设计,收集烟台市奇山医 院1月24日一2月28日COVID-19确诊患者病例的相关临床资料,应用实时荧光逆转录聚合酶链反应检测技术,在疾 病不同阶段采集鼻/咽拭子、痰液样本进行SARS-CoV-2核酸检测。对危(重)型及普通型患者的核酸阴转时间进行统 计学分析。 结果 共纳人71例确诊患者,男性40例,女性31例。患者首发症状80.3%为发热,57.8%为咳嗽。普通型 病例57例(占80.3%),轻型病例5例(占7.0%),重型病例8例(占11.3%),危重型病例1例(占1.4%)。治愈出院40例, 平均住院(22.78±6.19)d;鼻咽拭子和痰液样本在发病的1、2、3、4和5周的核酸检出率分别为100.0%和87.5%、48.6%和 88.2%、44.7%和86.1%、19.1%和58.7%、11.5%和33.3%。鼻咽拭子的假阴性率在发病的1、2、3、4和5周分别为12.5%、 52.9%、、44.1%、42.9%、20.0%。同期两种样本送检结果一致率在发病第1周及第5周较高;发病1周无病毒学核酸检测 阴转的病例,发病2周有2例(占3.9%),3周有12例(占23.5%),4周有20例(占39.2%),5周有16例(占31.4%),5周后 有1例(占2.0%)。第4~5周病毒核酸转阴率最高(占70.6%);危(重)型和普通型病人的核酸阴转时间分别为(30.00± 3.54)d和(24.00±5.84)d,差异有统计学意义(P<0.05)。 结论 COVID-19的主要症状为发热,干咳。普通型病例为主。 痰液样本核酸检测的阳性率高于鼻咽拭子样本,鼻咽拭子检测结果存在假阴性,两种样本联合送检可减少假阴性的发 生。在发病的第4周及第5周病毒核酸转阴率最高。重症患者病毒的持续存在,可能是病情加重的主要因素之一。

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          Author and article information

          China Tropical Medicine
          China Tropical Medicine (China )
          01 August 2020
          01 August 2020
          : 20
          : 8
          : 763-766
          1Yantai Qishan Hospital, Yantai, Shandong 264000, China
          Author notes
          Corresponding author: SUN Linlin, E-mail: sunlinlinyu0535@
          © 2020 Editorial Department of China Tropical Medicine

          This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 Unported License (CC BY-NC 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. See

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