key: cord-0857167-n30bu2nk
authors: Wang, Xiaoming; Zheng, Jingwei; Guo, Lei; Yao, Hao; Wang, Lingya; XiaoDong, Xia; Zhang, Weixi
title: Fecal viral shedding in COVID-19 patients: clinical significance, viral load dynamics and survival analysis
date: 2020-08-28
journal: Virus Res
DOI: 10.1016/j.virusres.2020.198147
sha: 4cfde5b4597b57892a4b3b11e12644ac8c586fb7
doc_id: 857167
cord_uid: n30bu2nk

BACKGROUND: To investigate the clinical significance, viral shedding duration and viral load dynamics of positive fecal SARS-CoV-2 signals in COVID-19. METHODS: COVID-19 patients were included. SARS-CoV-2 RNA was tested in stool and respiratory specimens until two sequential negative results were obtained. Clinical, laboratory and imaging data were recorded. RESULTS: Of the 69 COVID-19 patients, 20 (28.99%) had positive fecal viral tests who were younger, had lower C-reactive protein (CRP) and fibrinogen (FIB) levels on admission (all P < 0.05), and showed more improvement and less progression on chest CT during recovery. The median duration of positive viral signals was significantly longer in stool samples than in respiratory samples (P < 0.05). In spite of the negative oropharyngeal swabs, eleven patients were tested positive for viral RNA in stool specimens, with their fecal SARS-CoV-2 RNA Ct values reaching 25-27. 6 of these 11 patients' Ct (cycle threshold) values rebounded. CONCLUSION: SARS-CoV-2 RNA in stool specimens was associated with a milder condition and better recovery of chest CT results while the median duration of SARS-CoV-2 RNA persistence was significantly longer in fecal samples than in oropharyngeal swabs. The fecal viral load easily reached a high level and rebounded even though respiratory signals became negative.

countries, with more than 12 million people infected and over 550000 deaths globally.

SARS-CoV-2 belongs to beta-coronavirus genus lineage B and is phylogenetically closely related to bat SARS-like coronaviruses 1 . Infection with SARS-CoV-2 causes a spectrum of respiratory symptoms, including severe acute respiratory syndrome. COVID-19 spreads mainly via respiratory droplets and human-to-human contact [2] [3] [4] [5] . SARS-CoV-2 RNA has been reported to be detected in stool specimens from patients with COVID-19 [6] [7] . Furthermore, not only SARS-CoV-2 RNA but also intracellular staining of the viral nucleocapsid protein was found in gastric, duodenal and rectal epithelia [8] [9] [10] . Importantly, viral host receptor angiotensin converting enzyme 2 was positivity expressed in gastrointestinal epithelial cells 11 . These reports demonstrate that SARS-CoV-2 infection might occur in the gastrointestinal tract, which may result in transmission by the fecal-oral route. Most importantly, the risk of aerosol or contact transmission associated with fecal samples warrants more attention. Notably, clearance of viral RNA from patients' stool specimens requires more time than clearance from oropharyngeal samples [12] [13] . The dynamic changes in the viral load of prolonged SARS-CoV-2 RNA in stool specimens are not clear. In addition to the epidemiology, COVID-19 patients with gastrointestinal symptoms are more likely to test positive for viral RNA in stool, which is considered to be associated with prolonged symptoms [14] [15] . However, whether SARS-CoV-2 RNA in stool specimens has a strong relationship with the condition and prognosis of COVID-19 is unclear.

To further investigate the clinical significance, viral shedding duration and viral load dynamics of SARS-CoV-2 RNA in stool specimens, we compared the characteristics and prognoses of COVID-19 patients with positive and negative fecal viral tests, conducted a survival analysis of viral shedding durations in fecal and respiratory samples, and analyzed dynamic changes in fecal J o u r n a l P r e -p r o o f viral loads.

From February 6, 2020, to February Positive: a Ct value < 37.

A Ct value between 37-40 is indeterminate. It is required confirmation by repeating. If, when repeated, the Ct value is < 40 the sample with a obvious amplification peak, the sample is positive, otherwise, it is negative.

The date of disease onset was defined as the day of the onset of symptoms. Laboratory and chest CT examinations were conducted on admission and at the time of the last negative respiratory test and fecal test at least. Epidemiological data, clinical data, laboratory results and radiological findings were recorded, including sex, age, exposure history, familial aggregation, chronic medical illnesses, symptoms, neutrophil counts, leukocyte counts, lymphocyte counts, C-reactive protein 24 .56, and 21.48 corresponding to 1.5×104, 1.5×105, 1.5×106, and 1.5×107 copies per milliliter, respectively. All data were reviewed by two physicians.

Continuous variables are presented as the medians and interquartile ranges (IQRs). Nonparametric 

The comparison of clinical characteristics and laboratory and radiological findings between patients with positive and negative fecal viral tests is shown in Table 1 . Fever was more common in patients with negative fecal viral tests than in patients with positive viral tests (58% vs 22%, Wald chi-square=11.746, P=0.001).

Survival analysis showed no significant difference in the duration of positive signals for SARS-CoV-2 RNA in respiratory samples between patients with negative and positive fecal viral tests (P>0.05). The median survival of positive viral signals was significantly longer in fecal samples than that in oropharyngeal swabs (P<0.001, Figure 1 ). The median durations of positive signals for SARS-CoV-2 RNA were 25 days in fecal samples (95% CI, 23.55 to 26.45) and 16 days in oropharyngeal swabs (95% CI, 9.43 to 22.57) after symptom onset; therefore, the duration was approximately 9 days longer in fecal samples than in oropharyngeal swabs. In particular, positive fecal signals persisted for 49 days in patient I after symptom onset and for 33 days in patient G after viral tests in oropharyngeal swabs became negative.

To further understand the reason for the persistent positive fecal signals in 11 patients despite negative respiratory signals, Ct values, which are inversely related to the viral load, were recorded for fecal samples after the viral RNA test in oropharyngeal swabs became negative. As shown in 

The symptoms and laboratory and radiological findings of patients with either positive or negative SARS-CoV-2 RNA tests in stool samples at the time of the last negative respiratory sample are listed in Table 3 . We found that most of the symptoms and laboratory findings did not differ 2.04%, 15% vs 6.12%, 5% vs 2.04%; 0% vs 2.04%, 4.08%, 2.04%, 2.04%, 4.08%).

Clinical data, laboratory results and imaging examinations were compared at the times of the last negative viral respiratory tests and fecal tests in the 11 patients with a longer duration of positive fecal signals than positive respiratory signals, as shown in Table 4 

This study showed that 20 ( other study have reported that when a stool sample from a COVID-19 patient was used to inoculate naive ferrets they could isolate SARS-CoV-2 from the animals 33 . These results indicated that the clearance of the virus in stool might occur later than in the respiratory tract. It is possible that the virus in the digestive tract might remain alive for a long time, but requires further studies.. Since no differences in the duration of SARS-CoV-2 RNA persistence in respiratory samples were found between with positive and negative fecal tests, comparisons of symptoms and laboratory and radiological findings between with the two groups at the time of the last respiratory tests were discussed. We found that patients with positive fecal viral tests had higher proportions of complete absorption and no lesion progression in each lobe but no significant differences in most of the symptoms and laboratory findings compared with patients with negative fecal viral tests at the time of the last respiratory negative tests. In addition, Zheng S et al. reported that the viral shedding duration in respiratory samples was associated with disease severity 34 . These findings suggest that SARS-CoV-2 RNA in stool specimens is associated with better recovery of chest CT results.

Last, clinical data and laboratory and radiological findings were compared at the times of the last negative respiratory viral tests and fecal tests in the 11 patients with a longer duration of SARS-CoV-2 in fecal samples than in respiratory samples. We found no significant differences in clinical symptoms, leukocyte counts, lymphocyte counts, CRP levels, ALB levels or ALT levels, Data are presented as interquartile ranges (IQRs), numbers and percentages.

CRP, C-reactive protein; ALT, alanine transaminase; ALB, albumin.

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