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. 2020 Nov 2;18(1):411.
doi: 10.1186/s12967-020-02580-w.

Necessity for detection of SARS-CoV-2 RNA in multiple types of specimens for the discharge of the patients with COVID-19

Yongqing Tong  1 , Anyu Bao  1 , Hongbing Chen  2 , Jingtao Huang  1 , Zhihua Lv  1 , Lina Feng  1 , Yun Cheng  2 , Youna Wang  2 , Li Bai  1 , Wenlong Rao  1 , Hongyun Zheng  1 , Zegang Wu  1 , Bin Qiao  1 , Zhijun Zhao  3 , Huiming Wang  4 , Yan Li  5
Affiliations

Necessity for detection of SARS-CoV-2 RNA in multiple types of specimens for the discharge of the patients with COVID-19

Yongqing Tong et al. J Transl Med. .

Abstract

Background: The SARS-CoV-2 RNA was detected positive again after discharged from hospital in some COVID-19 patients, with or without clinical symptoms such as fever or dry cough.

Methods: 1008 severe COVID-19 patients, with SARS-CoV-2 RNA positive detected with the mixed specimen of nasopharyngeal swab and oropharyngeal swab by real-time fluorescence quantitative PCR (RT-qPCR), were selected to monitor SARS-CoV-2 RNA with the 12 types of specimens by RT-qPCR during hospitalization. All of 20 discharged cases with COVID-19 were selected to detect SARS-CoV-2 RNA in isolation period with 7 types of specimens by RT-qPCR before releasing the isolation period.

Results: Of the enrolled 1008 severe patients, the nasopharyngeal swab specimens showed the highest positive rate of SARS-CoV-2 RNA (71.06%), followed by alveolar lavage fluid (66.67%), oropharyngeal swab (30.77%), sputum (28.53%), urine (16.30%), blood (12.5%), stool (12.21%), anal swab (11.22%) and corneal secretion (2.99%), and SARS-CoV-2 RNA couldn't be detected in other types of specimen in this study. Of the 20 discharged cases during the isolation period, the positive rate of SARS-CoV-2 RNA was 30% (6/20): 2 cases were positive in sputum at the eighth and ninth day after discharge, respectively, 1 case was positive in nasopharynx swab at the sixth day after discharge, 1 case was positive in anal swab at the eighth day after discharge, and 1 case was positive in 3 specimens (nasopharynx swab, oropharynx swab and sputum) simultaneously at the fourth day after discharge, and no positive SARS-CoV-2 RNA was detected in other specimens including stool, urine and blood at the discharged patients.

Conclusions: SARS-CoV-2 RNA should be detected in multiple specimens, such as nasopharynx swab, oropharynx swab, sputum, and if necessary, stool and anal swab specimens should be performed simultaneously at discharge when the patients were considered for clinical cure and before releasing the isolation period.

Keywords: COVID-19; Discharge criteria; Multiple specimens; RT-qPCR; SARS-CoV-2.

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Conflict of interest statement

The authors declare that they have no competing interests.

Figures

Fig. 1
Fig. 1
Distribution of different types of specimens in COVID-19 patients. The 12 types of specimens collected from 8 types of tissues to monitor SARS-CoV-2 from the 1008 confirmed severe patient during hospitalization. The 12 types of specimens included nasopharyngeal swab, oropharyngeal swab, sputum, BALF, stool, anal swab, urine, PDF, blood, sweat, CSF, and corneal secretion. 8 types of tissues included respiratory tract, gastrointestinal tract, urinary system, blood, eyes, the nervous system and sweat gland. NS, nasopharyngeal swab; OS, oropharyngeal swab; BALF, bronchoalveolar lavage fluid; PDF, peritoneal dialysis fluid; CSF, cerebrospinal fluid
Fig. 2
Fig. 2
Positive rate of SARS-CoV-2 RNA detected in different specimens from COVID-19 patients. It was defined as positive when the ORF1ab gene and N gene were both positive at the same time. It was defined as suspicious when ORF1ab gene or N gene was positive, which should be resampled to detect again after 24 h
Fig. 3
Fig. 3
Positive rate of SARS-CoV-2 RNA detected in different specimens from the discharged COVID-19 patients in their isolation period. SARS-CoV-2 RNA was detected in 7 types of specimens before discharging. It could be considered positive when the ORF1ab and N genes were both positive at the same time. It could be considered that SARS-CoV-2 RNA was negative, and the virus was dead when only ORF1ab or N gene was positive
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