key: cord-0953270-wkc3p5d8
authors: Chen, Sheng-long; Xu, Hui; Feng, Hui-ying; Sun, Jiu-feng; Li, Xin; Zhou, Lin; Song, Wen-liang; Huang, Shan-shan; He, Jun-lei; Deng, Yi-yu; Wang, Rui-jie; Fang, Ming
title: Epidemiological and clinical findings of short-term recurrence of SARS-CoV-2 RNA PCR positivity in 1282 discharged COVID-19 cases: a multi-center, retrospective, observational study
date: 2020-09-13
journal: Open Forum Infect Dis
DOI: 10.1093/ofid/ofaa432
sha: f85f3cc75705547a75a52b7fe9050b623532bbc5
doc_id: 953270
cord_uid: wkc3p5d8

BACKGROUND: Short-term recurrence of positive SARS-CoV-2 RNA PCR in discharged COVID-19 patients attracts the public’s concern. This study aimed to determine clinical and epidemiological results of such patients. METHODS: This retrospective study was conducted on 32 designated hospitals for COVID-19 patients discharged from January 14 (th) to March 10 (th), 2020. After 28-day followed-up, re-positive patients confirmed by SARS-CoV-2 RNA RT-PCR were re-admitted to hospital for further treatments. All the close contacts of re-positive patients were asked 14-day self-segregating. Data of epidemiology, symptoms, laboratory tests and treatments were analyzed in re-positive patients and their close contacts were investigated. RESULTS: Of 1,282 discharged patients, 189 (14.74%) were tested re-positive of SARS-CoV-2 RNA during 28-day follow-up. The median time from discharge to re-positivity was 8 days (IQR 5-13). Patients in re-positive group were younger (34yr vs 45yr, p&0.001) with higher proportion of moderate symptoms (95.77% vs 84.35%, p&0.001) in the first hospitalization than negative group. During the second hospitalization, all re-positive patients showed normal in peripheral white blood cell and lymphocyte, and no new symptoms of COVID-19; 78.31% further improved on chest CT scan compared with the first discharge, yet 25.93% accepted antiviral therapy. The median time of re-positive to negative was 8 days (IQR 4-15). None of close contacts developed COVID-19. CONCLUSIONS: Our data suggested that the short term recurrence of positive SARS-CoV-2 RNA in discharged patients is not a relapse of COVID-19, and the risk of onward transmission is very low. This provides important information for managing COVID-19 patients.

As the pandemic of COVID-19 has swept across the globe, attentions have drawn to the epidemiological and clinical features of patients [1] [2] [3] , the therapeutic strategy [4] [5] , and the ways to increase cure rate and decrease mortality in countries and regions [6] . However, the knowledge about the novel COVID-19 was still limited, particularly in the management of convalescence stage after discharge.

With increasing numbers of patients that cured and discharged, we are facing serious problems as post-hospital surveillance and follow-up of COVID-19

patients. Some sporadic case reports from many cities in China, such as Wuhan [7] , Dongguan [8] , Weihai [9] , and Guangzhou [10] found that some patients detected recurrence of positive SARS-CoV-2 RNA PCR in nasopharyngeal swab or anal swab in 5-13 days after discharged from hospital. Recent report from Shenzhen city showed that the recurrence rate reached to 14.5% in 172 discharged patients [11] . Although these studies did not show the threat which was induced by the recurrence of positive for SARS-CoV-2 RNA, these findings aroused great concern of people since the definite pieces of evidence of highly human-to-human transmission were found in COVID-19 patients [12, 13] . Moreover, these archived studies were either case reports or small sized and single center studies with short follow-up period; therefore, it was hard to figure out the panorama of those populations with recurrence of viral RNA PCR positivity. In particular, the following questions were of great concern had not yet been answered clearly, e.g. 1) What is the ratio of re-positive patients in all discharged COVID-19 patients in Guangdong Province? 2) Does the recurrence of positive SARS-CoV-2 RNA mean COVID-19 would relapse such as other infectious diseases like typhoid fever [14, 15] ? 3) Are re-positive patients transmissible to others? Answering these questions has direct impacts on strategy formulation of disease control and prevention. Considering the ongoing A c c e p t e d M a n u s c r i p t 6 global pandemic of COVID-19, it is essential to carry out large scale studies to better understand the issue of recurrence of positive SARS-CoV-2 RNA in COVID-19 patients.

In response to these emerging concerns, we conducted a multi-center, retrospective, observational study of re-positive COVID-19 patients targeting to 1282 patients from 32 designated hospitals in Guangdong Province, China.

A multi-center, retrospective, observational study was conducted at 32 hospitals in Guangdong Province, designated to treat COVID-19 patients [16] . All confirmed COVID-19 patients who had discharged from Jan 14 th to Mar 10 th , 2020 were followed up for 28 days. According to the policy of Guangdong Province, the follow-up was divided into two stages. During the first stage, patients discharged before February 25th, 2020 were required self-segregating for 14 days (section A), while patients discharged after that time were mandatory to be quarantined in designated sites for 14 days (section B). Clinical symptoms (body temperature, cough and other respiratory symptoms) of them were recorded every day and SARS-CoV-2 RNA in nasopharyngeal and anal swabs specimens was tested every 3 days. During the second stage of 14-day follow-up, patients were self-segregated at home (section C) and the community members followed up their symptoms by telephone and carried out viral RNA test once a week. See the protocol in Figure 1 .

This study was authorized by the Guangdong Provincial Health Commission and was approved by the Ethics Committee of the Guangdong Provincial People's Hospital (No. GDREC2020028H). The whole course of treatment and follow-up for all COVID-19 patients were free. Data was collected by a public A c c e p t e d M a n u s c r i p t 7 health surveillance system-the electronic medical information reporting system (E-System)built by the Guangdong Health Commission, and every personal data was de-identified before analysis. Written informed consent was waived due to the use of de-identified data for the purpose of public health surveillance.

To ensure the quality and homogeneity of medical treatment, Guangdong COVID-19 Prevention and Control Headquarters was set up to direct and coordinate the management for COVID-19 patients across the province. An electronic medical information reporting system(E-System)was built by the Guangdong Health Commission for the entire provincial medical data collection, through which all data in this study were collected.

Information on demography, epidemiology, comorbidities and clinical data of the first hospitalization were collected; clinical symptoms monitoring and the SARS-CoV-2 RNA tests were made as described above. All re-positive patients (recurrence of SARS-CoV-2 RNA PCR positivity) were re-admitted to the hospital for observation or antiviral (Arbidol, Lopinavir & Ritonavir, etc.) treatment. Daily clinical symptoms (temperature, cough and other respiratory symptoms), laboratory tests were recorded.

All the close contacts of re-positive patients were asked self-segregating at home for 14 days. During the observation, their clinical symptoms were monitored every day and SARS-CoV-2 RNA in nasopharyngeal and anal swabs was detected every 3 days.

Swabs for detecting SARS-Cov-2 RNA were collected by qualified medical staff through standard procedures under level 3 biosafety protection according to the guidance of a previous study [17] [18] [19] . For nasopharyngeal specimens, a swab was inserted into the nostril parallel to the palate to a depth equal to the Moderate symptoms: fever and mild respiratory symptoms (cough, sore throat, runny nose, etc.), multiple patchy shadowing and ground-glass opacity in lung computed tomography (CT), and normal range of vital signs [3, 16] .

A c c e p t e d M a n u s c r i p t 9 Improvement of chest CT images Comparing to the last chest CT results, the size and density of pulmonary lesions are reduced; if the lesions significantly reduced by more than 50%, it is considered to be substantial improvement [14, 20] .

Close contacts Persons who have closely contacted with re-positive patients without effective protection with masks, such as living and working together, which confirmed by registered public health practitioners from Center for Disease Control and Prevention (CDC) [21] .

Both nasopharynx swabs and anal swabs samples from each re-positive patient were collected for the RT-PCR test in laboratory of the CDC of Guangdong Province. Once re-positive patients were reported by designated hospital, the A c c e p t e d M a n u s c r i p t

Continuous variables were expressed as median (IQR) and compared by Mann-Whitney U test, except for continuous variables of Ct value of RT-PCR which conform to normal distribution, were expressed as mean±standard deviation and 95% confidence interval (95% CI). Categorical variables were expressed as number (%) and compared by Chi-square test or Fisher's exact test as appropriate. A two-sided α of less than 0.05 was considered statistically significant. Statistical analyses were done using the SPSS, version 25.0.

In the first 14-day of follow-up, a total of 160 patients were tested re-positive for SARS-Cov-2 RNA, among them 111 re-positives were found from 809 discharged patients in section A, 49 re-positives from 473 cases in section B. The remaining 1122 cases were self-guarding during the following 14 days (section C), from which 29 re-positives were found. Compared with the negative group, the Re-positive group had a younger age (34yr vs 45yr， p<0.001) and more young components (63.49% vs 40.35% in 0-39 years range, P<0.001) (Table 1, Figure 2A ).

The median re-positive time from the first discharge was 8 days (IQR5-13), mainly concentrated in 15 days (90.48%), presented with 3 peaks at the 1 st , the 7 th and the 14 th day respectively ( Figure 2B , Table 2 ). Most of the recurrence for positive SARS-Cov-2 RNA (84.66%) occurred within 2 weeks, among which 54.50% were in the range of 0-39 years old ( Figure 2C ).

A c c e p t e d M a n u s c r i p t 11 

In clinic, comparing with negative patients, re-positive ones showed larger proportion of moderate symptoms (95.8% vs 84.4%, p<0.001) at the first admission, while less proportion of comorbidities(11.11% vs 22.69%， p<0.001) and lower incidence of fever (60.85% vs 68.34%, p=0.043) and cough (38.10% vs 49.77%, p=0.003). The clinical treatment protocol for repositive patients showed no difference with negative ones, including antivirals (84.66%), antibiotics (25.93%), corticosteroids (11.64%), and oxygen therapy (92.59%) for re-positive patients showed no difference with negative ones. The median length of the first hospitalization in re-positive patients was shorter than negative ones (17 days vs 19 days, p=0.013). The median time from the last negative to re-positive of viral RNA was 10 days (IQR 7-15) ( Table 1 ).

In total, 188 of 189 re-positive patients turned negative eventually during the second hospitalization in 1 to 37 days by April 7 th , 2020. The median conversion time from re-positivity was 8 days (IQR 4-15) ( Table 2 ). The majority (87.77%) of them conversed within 20 days, while 12.23% cases needed 21-37 days to recover ( Figure 3A ). 46.28% of re-negatives were 0-39 years old and conversed within 2 weeks ( Figure 3B ). The rest 1 patient didn't turn to negative until May 3 rd .

The median length of the second hospitalization for re-positive patients was 10 during the second hospitalization. White blood cell and lymphocyte account were within normal range either in the second admission (5.70×10 9 /L and 1.82 ×10 9 /L, respectively) or discharge (6.01×10 9 /L and 1.99×10 9 /L, respectively) from hospitalization. Chest CT scans also showed no aggravations (140 improved, 8 cured and 36 no remarkable changes) compared with the first discharge. Only 49 cases (25.93%) accepted antiviral therapy (Table-2 Based on the strict process of prevention and control policy in Guangdong Province, all positive results of RNA must be rechecked with the same source of samples within 24 hours and issued by the CDC of Guangdong Province before they were diagnosed as re-positives. We believe that the recurrence of positive viral RNA in all COVID-19 cases is universal. A recent small sized study in a neighbor city of Guangdong showed similar data with us [11] .

Secondly, we addressed that these re-positive of viral RNA means the continuation of the first infection, but not a re-infection of virus particles. 1) Epidemiological evidence. The median length of the first hospitalization of repositive cases was 17 days (IQR 13-23). It was reported that the specific antibody of IgG can be detected on the 4 th day after symptom onset, 85% of the patients could produce IgG on the 10 th -13 th day, and 100% on the 17 th day [23] , which supported that most of the patients in our study had produced specific antibodies at the time of discharge. Meanwhile, we combed the close contacts of the re-positive patients and found that they neither had been to the epidemic A c c e p t e d M a n u s c r i p t 14 area, nor exposed to COVID-19 patients. Even though an asymptomatic case of COVID-19 re-infection confirmed by whole genome sequencing was reported [24] , we noted that this case was diagnosed 142 days after the first symptomatic episode when he traveled Spain and United Kingdom and had a lot access to infected people. In this study, 49 discharged patients were tested recurrence of positive SARS-CoV-2 RNA during the mandatory quarantine period without contacting anyone but medical staff (section B of Figure- automatically. Therefore, our study suggested that short-term recurrence for positive SARS-CoV-2 RNA in discharged patients did not represent relapse of disease, but rather a phenomenon in a stage of viral clearance process.

Thirdly, we showed there was no communicability of re-positive patients in our data. None of the 209 close contacts of 69 patients developed clinical symptoms of COVID-19, e.g. fever or cough, and the RT-PCR were also tested A c c e p t e d M a n u s c r i p t 15 negative in both nasopharyngeal and anal swab samples. Therefore, it could be suggested that re-positive patients were barely communicable. Additional evidence was the viral load of SARS-CoV-2 in nasopharyngeal swab reached extremely low limits of detection until the 21 st day [25] . The live virus can only be isolated in nasopharyngeal swabs within 8 days after symptom onset with a viral load over than 10 6 copies/mL [26] . As the median 18 days of hospitalization at the first admission in this study, it was inferred the possibility of excreting live virus was extremely low. [27, 28] . In our data, the median hospitalization time for negative group patients was significantly longer than re-positive group, especially in the range of age<30yr. It was suggested that the insufficient length of hospital stay may be one of the explanations why the SARS-CoV-2 RNA was tested re-positive after discharge. Patients in the re-positive group showed younger, lower incidence of fever and cough at admission with less proportion of severe symptoms, but higher lymphocyte counts in the present study.

Although the younger and mild patients could recover with a shorter time of hospitalization, meeting the discharge criteria did not mean that the virus was completely cleared. Thus, the larger proportion of recurrence for positive SARS-CoV-2 RNA in younger patients may be related to shorter time of hospitalization.

There are limitations in our study. First, due to the complexity of the epidemic situation, we can not achieve a cohort-based design and implementation in a short period of time, nor can we identify the virus genotypes, which is a major defect of this paper. Second, serum antibody test and live virus isolation of re-positive patients had not been conducted in this study, and only less than half of re-positive patients were drawn for viral RNA A c c e p t e d M a n u s c r i p t 16 confirmation since total samples can not be obtained. Third, only 209 close contacts were generated in this study, which might not be enough to fully assess the risk for communicability.

In conclusion, this multi-center, retrospective, observational study with the large samples and 28-day follow-up among the discharged COVID-19 patients in Guangdong Province, China, we found out that the younger and better As shown in Figure-1 , during the first 14 days, patients discharged before February 25th, 2020 in Guangdong Province were required selfsegregating for 14 days (section A), while patients discharged after that time were mandatory to be quarantined in designated sites for 14 days (section B) and no close contact since then. During the second 14 days, patients were self-segregated at home (section C) and the community members followed up their symptoms by telephone and carried out viral RNA test once a week. Both section A and C would generate close contacts.

Once re-positive SARS-CoV-2 RNA was tested, a second test would be carried out within 24 hours to determine the re-positive patient (see definition). Lung CT was performed when positive SARS-CoV-2 RNA recurrence was confirmed. According to the results of SARS-CoV-2 RNA tests during follow-up, discharged patients were divided into re-positive group and negative group. Patients in re-positive group were admitted to the designated hospital for further observation and treatment, and were discharged again till they met the discharge criteria. Patients had finished the processes above were included in our study. As shown in Figure-2A , age pyramid count graph, patients of re-positive group account 12.70% in the range of 0-9yr, 7.94% in 10-19yr, 19 .58% in 20-29yr, 23.28% in 30-39yr,11.64% in 40-49yr,11.11% in 50-59yr, 11 .64% in 60-69yr, 2.12% in ≥70yr, while patients in negative group account 3.20% in the range of 0-9yr, 3.39% in 10-19yr, 10 .89% in 20-29yr, 22.87% in 30-39yr, 17.02% in 40-49yr, 19 .85% in 50-59yr, 17.93% in 60-69yr, 4.85% in ≥70yr. Figure 

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