Value of Viral Nucleic Acid in Sputum and Feces and Specific IgM/IgG in Serum for the Diagnosis of Coronavirus Disease 2019.

Yuwen He,Jinlong Song,Jiangyan Luo,Weifeng Ma,Jie Yang,Li Wei

doi:10.3389/fcimb.2020.00445

Abstract

A new type of coronavirus-induced pneumonia eventually termed “coronavirus disease 2019” (COVID-19) was diagnosed in patients in Wuhan (Hubei Province, China) in December 2019, and soon spread worldwide. To improve the detection rate of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), we analyzed the results of viral nucleic acid and serum-specific antibody tests on clinical samples from 20 patients with SARS-CoV-2 infection diagnosed at the First Affiliated Hospital of Guangzhou Medical University in China. By comparing various sample types collected from COVID-19 patients, we revealed multiple pathways for SARS-CoV-2 shedding, and a prolonged detectable period for viral nucleic acid test in sputum specimens, demonstrating that the timeline of the viral shedding is of great value in determining the time of release from quarantine or discharge from hospital. We also recommend for the application of serological test to assist in confirming SARS-CoV-2 infection judged by viral nucleic acid test, especially when COVID-19-related symptoms have appeared and the viral nucleic acid test was negative. Our findings are critical for the diagnosis of SARS-CoV-2 infection and for determining deadline of restriction measures to prevent transmission caused by convalescent patients with COVID-19.

Highlights

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), identified in Wuhan, China at the end of 2019, spread rapidly worldwide
The discharge criteria include: (i) Body temperature returned to normal for more than 3 days; (ii) Respiratory symptoms were significantly improved; (iii) Chest images showed that acute exudative lesions were significantly improved; (iv) Viral nucleic acid tests were negative in sputum, nasopharyngeal swabs, and feces samples for two consecutive times
Since COVID-19 was first prevalent in China, we successfully demonstrated the whole process from diagnosis to discharge, while other areas may have not detected until the endpoints of some critically ill patients from the beginning of the epidemic to the present

Summary

Introduction

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), identified in Wuhan, China at the end of 2019, spread rapidly worldwide. In order to diagnose a large number of patients, samples of lower respiratory tract such as sputum with high positive rate are generally collected for viral nucleic acid detection (Han et al, 2020; Qu et al, 2020). Some studies have reported the presence of viruses in feces (Tang et al, 2020; Wu et al, 2020), implying the risk of fecal-oral transmission, and indicating that specimen collection should not be limited to respiratory samples. It is necessary to deliver viral nucleic acid and serological tests for people with a history of exposure to SARS-CoV-2. We undertook a study on the viral nucleic acids of SARS-CoV-2 in swabs (nasal, pharyngeal), sputum and feces, as well as antibodies in the serum of COVID-19 patients admitted to the First Affiliated Hospital of Guangzhou Medical

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