SARS-CoV-2 viral shedding characteristics and potential evidence for the priority for faecal specimen testing in diagnosis.

Chen Yuan,An Tang,Jiabei Chen,Mingyu Wu,Yongli Zhang,Haodi Xu,Jianbo Yan,Wenjie Wu,Hai Wang,Zhendong Tong,Bing Wu,Shelan Liu,Hongling Wang,Menglu Yu,Hui Zhang,Kefeng Li,Yuchao Wang,Xinwei Yu,J He ,Gu Song-Ye ,Yongyu Dai ,Jie-Nan Liu

doi:10.1371/journal.pone.0247367

Abstract

This study aimed to identify the specimen type that has high positivity and its proper sampling time for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) testing to promote diagnostic efficiency. All SARS-CoV-2-infected patients with a laboratory-confirmed diagnosis in Zhoushan City were followed up for viral shedding in respiratory tract specimens and faecal samples. Positivity was analysed both qualitatively and quantitatively by proper statistical approaches with strong testing power. Viral shedding in respiratory tract and faecal specimens was prolonged to 45 and 40 days after the last exposure, respectively. The overall positive rate in respiratory tract specimens was low and relatively unstable, being higher in the early-to-mid stage than in the mid-to-late stage of the disease course. Compared with respiratory tract specimens, faecal samples had a higher viral load, higher overall positive rate, and more stable positivity in different disease courses and varied symptomatic status. Faecal specimens have the potential ability to surpass respiratory tract specimens in virus detection. Testing of faecal specimens in diagnosis, especially for identifying asymptomatic carriers, is recommended. Simultaneously, testing respiratory tract specimens at the early-to-mid stage is better than testing at the mid-to-late stage of the disease course. A relatively small sample size was noted, and statistical approaches were used to address it. Information was missing for both specimen types at different stages of the disease course due to censored data. Our research extends the observed viral shedding in both specimen types and highlights the importance of faecal specimen testing in SARS-CoV-2 diagnosis. Healthcare workers, patients, and the general public may all benefit from our study findings. Disposal of sewage from hospitals and residential areas should be performed cautiously because the virus sheds in faeces and can last for a long time.

Highlights

Coronavirus disease (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has rapidly spread worldwide
Equivocal results of 9 respiratory tract specimens and 1 faecal specimen were reported, and the corresponding participants all had a confirmed diagnosis based on tests conducted on other dates
Specimens collected from 117 participants from the Influenza-Like Illness (ILI) surveillance programme and 18 from the severe acute respiratory infection (SARI) surveillance programme testing for both SARS-CoV-2 and influenza (A/H3N2, A/H1N1, B) reported no co-infection of SARS-CoV-2 and influenza

Summary

Introduction

Coronavirus disease (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has rapidly spread worldwide. Fluorogenic real-time quantitative polymerase chain reaction (RT-qPCR) assay and genome sequencing are two techniques widely used in viral nucleic acid detection, and the former is usually preferred over the latter in SARS-CoV-2 testing and diagnosis. This is because the RT-qPCR assay overcomes the limitations of genome sequencing in aspects such as a high error rate, high technical requirements, insufficient reliability of antibody reagents, and low cost-effectiveness [3]. Understanding the viral shedding pattern is helpful for timely and efficient diagnosis, which plays a decisive role in identifying the infection source, prompt isolation, conducting treatment, ending quarantine for the infected person, and disease prevention and control among the population

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