key: cord-0832214-586dhsk9 authors: Zhang, Jintao; Xu, Jiawei; Zhou, Shengyu; Wang, Chunting; Wang, Ximing; Zhang, Wei; Ning, Kang; Pan, Yun; Liu, Tian; Zhao, Jiping; Dong, Liang title: The characteristics of 527 discharged COVID-19 patients undergoing long-term follow-up in China date: 2021-02-01 journal: Int J Infect Dis DOI: 10.1016/j.ijid.2021.01.064 sha: 691cfffdbf1a6058c9327e7340104b86bea4ea48 doc_id: 832214 cord_uid: 586dhsk9 BACKGROUND: Almost a year after the outbreak of coronavirus disease 2019 (COVID-19), numerous hospitalized COVID-19 patients have recovered. However, little is known about the long-term follow-up (>2 months) of discharged patients. METHODS: We enrolled 527 discharged COVID-19 patients in a study from February 5 to March 11, 2020. These patients’ basic characteristics, imaging features, nucleic acid detection results, and antibody levels were retrospectively reviewed. RESULTS: of the 527 discharged patients, 32 (6.1%) had re-detectable positive (RP) nucleic acid results for SARS-CoV-2 during follow-up examinations with 11 and four detections entailing stool samples and anal swabs, respectively, rather than respiratory samples. Juveniles were more accessible to “infection recurrence” than other age groups, with shorter time spans for RP RNA tests (an average of 8.8 days [6.0–9.0 days]), while the reverse was true for the middle-aged group (17.5 days on average [14.0-17.5 days]). Similar improvements in the imaging features of both RP and none RP (NRP) groups were observed. Negative antibody detections in patients 3 and 6 months after discharge were 14.2% and 25.0%, respectively. Cases evidencing negative antibodies were more common among juvenile patients (40% vs. 15.6%, p = 0.03) 6 months post-discharge. CONCLUSIONS: 6.1% of 527 discharged patients showed RP status, which may be easier to be identified from stool samples than from other samples. Given the dropping rate of SARS-CoV-2 antibody, reinfection may happen especially in juvenile patients (age less than 18 years). Our findings have implications for the long-term management of recovered COVID-19 patients. Among existing viruses, coronaviruses, which have the largest RNA genome have attracted considerable attention in the light of the recent emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (Zhou P et al., 2020) . Coronavirus disease 2019 , which is caused by SARS-CoV-2, has prompted a pandemic, posing global health challenges. As of September 11, 2020, J o u r n a l P r e -p r o o f 280,418,42 COVID-19 cases had been diagnosed globally, resulting in 906,094 deaths. In China, 90643 cases have been diagnosed, of whom 85505 have been cured and discharged from the hospitals where they were treated (2020). In recent months, multiple studies have described the clinical characteristics of COVID-19 (Chen N et al., 2020 . With rising numbers of clinically cured patients, research on individuals discharged from hospitals is expanding (Bowles et al., 2020 , Lan et al., 2020 . In compliance with the criteria for hospital discharge in China, these "recovered" patients generally had no clinical symptoms and tested negative in two reverse transcription polymerase chain reaction (RT-PCR) tests performed 24 hours apart. However, given uncertainty regarding the infectivity and health status of discharged COVID-19 patients, appropriate epidemic prevention and control measures remain unclear. A recent postmortem pathological study conducted on a COVID-19 patient whose throat swabs produced negative results for the SARS-CoV-2 nucleic acid test on three consecutive occasions revealed residual virus in the pneumocytes (Yao et al., 2020) . Moreover, several studies have reported re-detectable positive (RP) SARS-CoV-2 nucleic acid test results for some discharged patients , Lan et al., 2020 . Until now, it is still unclear whether RP patients could transmit the virus and infect others. Therefore, studies that determine the prognostic status of discharged patients and identify factors affecting RP would contribute to preventing the pandemic's spread. The discovery of RP patients has also raised concerns about J o u r n a l P r e -p r o o f hospital discharge standards relating to COVID-19. Up to now, few studies have focused on recovered patients, especially those discharged with a long follow-up duration (>two months), which limits a comprehensive understanding of the disease. More such studies would contribute to refining clinical guidelines for containing and managing COVID-19. In Shandong, where follow-up of discharged COVID-19 patients is mandatory for a six-month period, some cured COVID-19 patients had RP RT-PCR test results along with certain significant traits. While reviewing these patients' long-term follow-up data, we also examined their post-recovery conditions, including imaging features and antibody levels. Our findings will provide valuable inputs for the management of convalescing COVID-19 patients. We analyzed the data of 527 discharged patients (294 male, 233 female) from designated hospitals for treating COVID-19 patients in Shandong, China. The patients were admitted to hospitals with confirmed SARS-CoV-2 infections between January 21 and February 16, 2020 during the early phase of this pandemic. The discharge criteria for recovered patients , were as follows: (1) a normal body temperature for more than 3 days, (2) significantly improved respiratory symptoms, (3) significant improvement of acute exudative lung lesions confirmed through CT imaging, and (4) negative results for nucleic acid tests using respiratory tract samples on two consecutive occasions (with a sampling interval of at least 24 hours). RP patients were defined as discharged patients with re-detectable positive nucleic acid test results using any sampling means. The severity of the disease was categorized according to the "Guideline on the management of COVID-19" published by the National Health Commission of the People's Republic of China. Mild cases evidenced mild symptoms and no imaging observations of pneumonia. Severe cases displayed one of the following characteristics: dyspnea with a respiratory rate ≥30 breaths per min, oxygen saturation ≤93%, or arterial blood oxygen partial pressure (PaO2)/oxygen concentration (FiO2) ≤40 kPa. We reviewed all of the patients' medical records and radiological report results stored in the electronic medical system. The baseline data and information collected from patients included sex, age, residential location, hospitals of initial attendance and discharge, date of disease onset, and admission and discharge times. The collection of samples for the SARS-CoV-2 test from the patients' sputum, throat and anal swabs, and stool samples complied with the "Technical guidelines for COVID-19 laboratory testing, version 2." Pathogen testing was performed using an Continuous results were expressed as average and interquartile ranges (IQRs), and dichotomous variables were presented as n (percentages). We calculated parameter differences using the Mann-Whitney U test, 2 test, or Fisher's exact test, as appropriate. A two-sided α under 0.05 was considered statistically significant. We obtained data for 527 discharged patients from designated hospitals for middle-aged, 29.4%; elderly patients, 15.8%) ( Figure 1A ). The RP patients were, on average, younger than the NRP patients (32.5 [IQR13.3-42.5] years vs 43.1 [IQR33.0-54.0] years). Infection recurrence was more common among juvenile patients than among other age groups, while the reverse was true for middle-aged patients ( Table 1 ). None of the RP patients experienced severe or critical COVID-related symptoms during their previous hospitalization ( Table 1 ). The average duration from the onset of symptoms to admission was 4.4 days (1.0-6.0 days) for all patients, while that from admission to discharge was 20.1 days (14.0-25.0 days). There were no significant differences between the RP and NRP groups for the durations from illness onset to admission and from admission to discharge. evidenced the shortest RP time ( Figure 1C ). Rapid and accurate diagnostic tests are essential for controlling the ongoing COVID-19 pandemic. In our study, throat swabs were obtained from all 32 RP patients, and 16 patients tested positive for the nucleic acid test. In addition to positive test results obtained for throat swabs, fourteen, three, and four patients respectively tested positive in the nucleic acid test for their stool samples, sputum samples, and anal swabs (Figure 2A , H). Notably, 16 RP patients were identified independently of throat swab (11 through stool samples, one though a sputum sample, and four through anal swabs) ( Figure 2H ). Strikingly, after patients were grouped according to the time of their RP diagnosis we found that the positive rate of nucleic acid detection from the stool samples of patients who recovered within 14 days was much higher than that for throat swabs ( Figure 2B -C). To ascertain the reason, we searched the GTEx and FANTOM5 datasets and found that ACE2 and TMPRSS2, which are two essential J o u r n a l P r e -p r o o f proteins used by SARS-CoV-2 to penetrate cells, have the highest expression levels in the digestive organs (i.e., small intestine, stomach and colon) ( Figures 2D-G) , may partially explain why the virus nucleic acid is more likely to be detected in the RP patients' feces, which is a digestive tract secretion. In other words, the virus may not have been totally cleared from the systems of patients who met the hospital discharge standard at the time of their discharge, and it may continue to hide in their digestive organs. Table 3 , the antibody test was administered to 127 patients (69 males and 58 females) and 64 patients (30 males and 34 females) three months and six months, respectively, after discharge. Evidently, the negative rate of SARS-COV-2 antibodies occurred more in juvenile patients (40.0%), but, as Table 3 shows, there was no difference in these rates for male and female patients. Chest computed tomographic ( Data are presented as the n (n/N%), where N denotes the total number of patients for whom data were available. At present, there is a lack of research in the light of discharged COVID-19 patients. To our knowledge, this is the first study to investigate the recovered COVID-19 patients undergoing long-term follow-up. This study entailed a comprehensive analysis of clinical and follow-up data compiled for 527 discharged patients. Its findings can provide valuable inputs into policies on infection prevention and prognosis management post-discharge. A growing body of evidence has revealed that varying disease intensities and J o u r n a l P r e -p r o o f patients' immune responses to the disease, drug utilization, sampling sites, and processing methods may all affect virus detection results and lead to RP test results for discharged COVID-19 patients (Mei et al., 2020 , Yan et al., 2020 . It is widely acknowledged that the clinical manifestations of COVID-19 are associated with age and that patients manifesting severe COVID-19 symptoms are almost all either elderly or already suffering from chronic diseases (Chen G. et al., 2020 , Chen N et al., 2020 . In our study, none of the 46 (8.7%) patients with severe symptoms were RP, although there were no statistical differences in the proportions of RP and NRP patients with severe symptoms, possibly because of the limited sample size. According to the date from early outbreaks in China, the SARS-CoV-2 infection rate among children was lower than that of adults . Previous studies have also reported milder symptoms and faster clinical remission among juveniles with SARS-CoV-2 infections compared with adults (Pierce et al., 2020 . Our finding that juvenile patients displayed several distinct features like a higher incidence rate of RP and a shorter time before a re-detectable positive diagnosis is consistent with that of previous reports Figure) . These results indicate that children recover quickly and their prognoses are favorable; a finding that may be linked to their balanced immune responses rather than to their abilities to clear viruses J o u r n a l P r e -p r o o f rapidly and strong adaptive immune responses (Pierce et al., 2020 . In other words, possibly because of the early discharge of juvenile patients, the virus in their bodies is not completely cleared, which may induce the high RP rate. Our results suggest that caution is required in the treatment of discharged patients, especially juveniles, who do not display any symptoms but in whom residual virus may still be present. Another important factor influencing RP pertains to long-term virus residual levels in the gut and in other tissues, given their high ACE2 and TMPRSS2 content. Samples from the upper respiratory tract are commonly used and are the current standard samples used for nucleic acid testing to detect SARS-CoV-2 infections . Prolonged shedding of SARS-CoV-2 in stool specimens of infected individual raises the possibility that the virus might be detected from many sources besides throat swabs after discharge. In this study, 15 patients, whose RNA extracted from throat swabs tested negative, were diagnosed as RP according to the results obtained for their fecal samples and anal swabs. One study conducted on 41 COVID-19 patients showed that the continuous duration of stool samples that tested positive was 11.2 days longer than the duration of respiratory samples that tested positive . They also found that SARS-CoV-2 nucleic acid can even persist in the digestive tract and feces for nearly 50 days . Consequently, the rate of positive results for fecal samples exceeded that for throat swabs obtained from discharged patients, which partially accounts for the RP J o u r n a l P r e -p r o o f phenomenon. Because the virus may remain in the digestive organs for a longer time than in the respiratory organs, positive results are more likely to occur for stool samples or anal swabs collected from discharged patients compared with other detection means. Other studies have also suggested that virus detection targeting the gastrointestinal tract may provide a more accurate assessment of therapeutic efficacy and recovery . Accordingly, future studies should focus on applying more precise and sensitive detection methods for different patients of different ages and at varying stages of illness to reduce the incidence of RP and the risk of the virus re-spreading. It has been known that individuals infected with SARS-CoV-2 will have a strong immune response and produce a large quantity of neutralizing antibodies (Juno et al., 2020) . As shown in pie chart, RP and NRP patients are seems to display different plasma IgG and IgM levels after discharge. A recent research reported that durable production of antibodies against SARS-CoV-2 lasting at least 2-3 months after illness onset (Ripperger et al., 2020) . In compliance with previous research, SARS-CoV-2 antibody of 14.7% patients in our data return to baseline levels within 3 months after discharge. Edridge et al. reported that reinfections of the four coronaviruses that cause the common cold occur after an average of 12 months (Edridge et al., 2020) . Over (Goldman et al., 2020) . Therefore, the potential for SARS-COV-2 reinfection and continued transmission to occur after hospital discharge requires attention. Notably, we also found that the rate of disappearance of antibodies at 6 months after discharge is highest in juvenile patients (age less than 18 years) compared with other age groups. As mentioned, under SARS-CoV-2 infection, the intensity of immune response especially adaptive immune response of children may not as high as adults (Pierce et al., 2020) . Existed research had shown that the types of antibodies induced by SARS-CoV-2 differ in children and adults (Weisberg et al., 2020) . The IgG antibody, which can recognize the spike protein, is produced in children. By contrast, adult patients produce more varieties of antibodies with a stronger ability to defend against not only spike proteins but also many other viral proteins (Weisberg et al., 2020) . These findings may partly explain the reason why the antibodies of the juvenile group in our study disappeared in advance. However, given quantitative data gaps, more research is needed to provide convincing evidence. Combining assessments of CT findings with clinical and laboratory findings could assist in the diagnosis and management of patients with COVID-19 , Shi et al., 2020 . In our study, continuous observations over time revealed improvements in imaging features among all patients. The lung imaging reports for RP and NRP patients showed no significant differences, indicating that sustained remission or no lesions in the lungs occurred among both groups. Previous study showed that abnormal chest radiographs were seen in 30% of SARS patients 6 months J o u r n a l P r e -p r o o f after infection (Hui et al., 2005) . Interestingly, HRCT scan showed no significant difference between mechanically ventilated and non-mechanically ventilated SARS patients (Joynt et al., 2004) . In our data, we also observed the relatively high rates of persistent radiological abnormalities at 6 months. Due to the limitations of our study, the reasons for this phenomenon remain to be validated in the future. Currently, no study has been able to provide an accurate estimate of the infection period for this novel coronavirus. None of the discharged patients in our six-month study, including RP patients, passed the infection on to others. Some studies have suggested that in most cases, SARS-CoV-2 loses its infectivity by the tenth day post-symptom onset or after the first positive PCR result (Sze et al., 2020) . The literature does not contain any reports on RP relating to other highly pathogenic coronaviruses, such as SARS-CoV and the Middle East Respiratory Syndrome (MERS)-CoV, possibly because of high associated mortality rates and the small numbers of infected people (Peeri et al., 2020) . Compared with other highly pathogenic coronaviruses, COVID-19 not only spreads faster and more widely but may also have a more complex infection course (Peeri et al., 2020) . This study had several limitations. First, there were missing rates for some key indexes given that this was a retrospective study, entailing a long follow-up duration. The number of cases examined in our study may not have been sufficient to fully reveal all of the key factors for specific data, which may therefore have been underestimated. Moreover, we also lack of data about clinical status of patients during J o u r n a l P r e -p r o o f follow-up. More compact designs and scientific clinical trials are required to evaluate the potential risk of SARS-CoV-2 RP test results. Another limitation was that dynamic changes of serum-specific antibody levels in RP patients were not quantifiable. Differences between RP and relapsed patients in which distinct prevention and control strategies are adopted should also be compared. In conclusion, we screened discharged patients undergoing 6 months follow-up, including their basic characteristics, nucleic acid test results obtained using different sampling methods, imaging features, and antibody detection results. Therefore, our study provides a foundation for studying hospital policies for SARS-CoV-2 and their discharge standards. We have also provided inputs that can facilitate treatment planning and the study of changing conditions of patients who have been infected with SARS-CoV-2. With the progressive emergence of novel coronaviruses, it is essential to ascertain the complete mechanisms in infected and recovered subjects to enable people to protect themselves. Currently, discharge criteria for hospitalized COVID-19 patients exhibit considerable heterogeneity across different countries (Sze et al., 2020) . In the current context of a global pandemic, more in-depth studies focusing on recovered COVID-19 patients are urgently needed to explore the possibility of standardizing discharge criteria, containing the spread of the disease, and even improving prognosis. This work was supported by grants from the National Natural Science Foundation of China (81770029) and National Key Research and Development Project (2017YFC1310601). The funders had no role in the study design, data collection, data analysis or preparation of the manuscript. The data used and analyzed during this research are available from the corresponding author on reasonable request. This was a retrospective study and all patient data accessed complied with relevant data protection and privacy regulations. LD conceived and designed the study, had full access to all of the data in the study, and took responsibility for the integrity of the data and the accuracy of the data analysis. JTZ drafted the paper and performed the analysis. JWX, SYZ, CTW, XMW, WZ, KN, YP, TL and JPZ collected the key data and critically reviewed the article before submitting it. All authors made substantial contributions to this manuscript and agree to be accountable for all aspects of the work. 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(G): Nucleic acid test results for 32 RP patients using different sampling methods Antibody levels in discharged patients at different time points Antibody levels of RP patients post-discharge at different time points (4 weeks Antibody levels of NRP patients post-discharge at different time points (4 weeks, 3 months, and 6 months) The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.J o u r n a l P r e -p r o o f The authors declare no conflicts of interest.