Positive result of Sars‐Cov‐2 in faeces and sputum from discharged patients with COVID‐19 in Yiwu, China

Abstract Background With the effective prevention and control of COVID‐19 in China, the number of cured cases has increased significantly. Further monitoring of the disease prognosis and effective control of the “relapse” of the epidemic has become the next focus of work. This study analysed the clinical prognosis of discharged COVID‐19 patients by monitoring their SAR‐CoV‐2 nucleic acid status, which provided a theoretical basis for medical institutions to formulate discharge standards and follow‐up management for COVID‐19 patients. Methods We included 13 discharged COVID‐19 patients who were quarantined for 4 weeks at home. The patient's daily clinical signs were recorded and sputum and faecal specimens were regularly sent for detection of SARS‐CoV‐2 nucleic acid. Results The time between initial symptoms and meeting discharge criteria was 18 to 44 days with an average of 25 ± 6 days. The faecal samples of two patients still tested positive after meeting the discharge criteria and the sputum samples of four patients returned positive 5 to 14 days after discharge. The rate of the recurring positive test result in samples from the respiratory system was 31% (4/13). Conclusion Under the present discharge criteria, the high presence of SARS‐CoV‐2 nucleic acid in faecal and respiratory samples of discharged COVID‐19 patients indicates potential infectivity. Therefore, we suggest that faecal virus nucleic acid should be tested as a routine monitoring index for COVID‐19 and a negative result be added to the criteria. Simultaneously, we should strengthen the regular follow‐up of discharged patients with continuous monitoring of the recurrence of viral nucleic acid.

significantly. Further monitoring of the disease prognosis and effective control of the "relapse" of the epidemic has become the next focus of work. As one of the designated hospitals for the diagnosis and treatment of COVID-19, all patients in our hospital met the discharge criteria after treatment as described in "Diagnosis and Treatment Scheme of New Coronavirus Infected Pneumonia (trial version 5)". 6 The aim of this study is to analyse the causes of viral nucleic acid re-emergence by investigating the follow-up data of COVID-19 patients who met the discharge criteria.
This may provide evidence that medical institutions should strengthen the follow-up management of discharged COVID-19 patients.

| Study population
We recruited 13 patients who were diagnosed as COVID- 19

| Follow-up observation and monitoring indicators
Oral swabs, nasal swabs, sputum, blood, faeces, urine, vaginal secretions, and milk of COVID-19 patients were collected for viral nucleic acid test upon hospitalisation. After COVID-19-confirmed patients meet the discharge criteria, they should: (a) Be quarantined for 4 weeks at home (b) wear medical masks when leaving home and keep distance with others to reduce contact (c) attend a follow-up visit in the first, second, and fourth week after discharge with sputum and faecal viral nucleic acid tests, routine blood examination, biochemistry tests including C-reactive protein, and lung CT scan. (d) Monitor body temperature and other symptoms daily during isolation. If any symptoms such as fever, cough, sore throat, fatigue, and muscle soreness are found, patients should immediately return to the hospital to determine the respiratory and faecal virus nucleic acid status.

| Data acquisition
Baseline information, laboratory and imaging examinations, diagnosis, and treatment process of the included cases were obtained from the electronic medical record system. All information was obtained and curated with a standardised data collection form. Two researchers independently reviewed the data collection forms.

| Viral nucleic acid test results before discharge
We tested each type of specimen more than 3 times for SARS-CoV-2 nucleic acid upon hospitalisation. Test results showed that the positive rate in sputum was 100% (13/13), oral swab was 40% (4/10), nose swab was 75% (9/12), and faeces was 38% (5/13). Concurrently, the urine and blood viral nucleic acid of all 13 patients tested negative. Similarly, the vaginal secretions of the six female patients tested negative and the milk of one lactating patient was also negative (Table 2 and Figure 1).

| Follow-up results of patients after meeting discharge criteria
In subsequent monitoring of the viral nucleic acid status of dis-   There may be three possibilities for the recurrence of viral nucleic acid in discharged patients. One possibility is that the test results before discharge were false negative due to a flawed sample. It has been reported that the detection rate of viral nucleic acid in oral swabs is only 30-50% and is higher in nasal swabs. In comparison, the detection rate in the sputum is higher than that of both nasal and oral swabs. 12  To determine whether these viral nucleic acid relapsing patients are infectious, we need to consider two factors. One is to clarify the relationship between the chance of viral transmission and viral load in patients. We can then determine the viral load in relapsing patients to assess their infectiousness. Second, it is necessary to distinguish whether the viral nucleic acid positivity of discharged patients is due to residual virus or active replication. Currently, these factors remain to be elucidated. Therefore, without clear evidence that discharged patients are not infectious, the patients themselves and others will be at great risk if they are not adequately followed-up and strictly isolated after discharge.

| CONCLUSION
In view of the current discharge criteria, the presence of viral nucleic acid in the faeces and the rate of recurrence in the sputum of discharged patients have led us to propose the following suggestions.
First, it may be necessary to reassess the suitability of the current  organized by Projekt DEAL.

DATA AVAILABILITY STATEMENT
With the permission of the corresponding authors, we can provide participant data without names and identifiers, but not the study protocol, statistical analysis plan, or informed consent form. Data can be provided after the article is published. Once the data can be made public, the research team will provide an email address for communication.
The corresponding authors have the right to decide whether to share the data or not based on the research objectives and plan provided.