Nucleic Acid Test Results Research Articles

COVID-19 Mortality Prediction From Deep Learning in a Large Multistate Electronic Health Record and Laboratory Information System Data Set: Algorithm Development and Validation.

BackgroundCOVID-19 is caused by the SARS-CoV-2 virus and has strikingly heterogeneous clinical manifestations, with most individuals contracting mild disease but a substantial minority experiencing fulminant cardiopulmonary symptoms or death. The clinical covariates and the laboratory tests performed on a patient provide robust statistics to guide clinical treatment. Deep learning approaches on a data set of this nature enable patient stratification and provide methods to guide clinical treatment.ObjectiveHere, we report on the development and prospective validation of a state-of-the-art machine learning model to provide mortality prediction shortly after confirmation of SARS-CoV-2 infection in the Mayo Clinic patient population.MethodsWe retrospectively constructed one of the largest reported and most geographically diverse laboratory information system and electronic health record of COVID-19 data sets in the published literature, which included 11,807 patients residing in 41 states of the United States of America and treated at medical sites across 5 states in 3 time zones. Traditional machine learning models were evaluated independently as well as in a stacked learner approach by using AutoGluon, and various recurrent neural network architectures were considered. The traditional machine learning models were implemented using the AutoGluon-Tabular framework, whereas the recurrent neural networks utilized the TensorFlow Keras framework. We trained these models to operate solely using routine laboratory measurements and clinical covariates available within 72 hours of a patient’s first positive COVID-19 nucleic acid test result.ResultsThe GRU-D recurrent neural network achieved peak cross-validation performance with 0.938 (SE 0.004) as the area under the receiver operating characteristic (AUROC) curve. This model retained strong performance by reducing the follow-up time to 12 hours (0.916 [SE 0.005] AUROC), and the leave-one-out feature importance analysis indicated that the most independently valuable features were age, Charlson comorbidity index, minimum oxygen saturation, fibrinogen level, and serum iron level. In the prospective testing cohort, this model provided an AUROC of 0.901 and a statistically significant difference in survival (P<.001, hazard ratio for those predicted to survive, 95% CI 0.043-0.106).ConclusionsOur deep learning approach using GRU-D provides an alert system to flag mortality for COVID-19–positive patients by using clinical covariates and laboratory values within a 72-hour window after the first positive nucleic acid test result.

Epidemiological Characteristics and Core Containment Measures of Imported COVID-19 Cases from Abroad in Early Phase in Guangdong, China.

ObjectiveThis study aimed to analyze the distribution characteristics and influencing factors for the interval between entering mainland China and the diagnosis of imported COVID-19 cases in Guangdong province, in order to provide valuable experience for global pandemic in prevention and control.MethodsWe collected publicly reported data between March 1 and June 2, 2020. Univariate and multivariate regression analyses were performed to identify the significant associated factors with the interval between entering mainland China and diagnosis of imported COVID-19 cases.ResultsAs of June 2, 2020, a total of 200 imported cases were reported in Guangdong province. The average interval time was 4.25 days with a median of 2 days, the interval time of 68% cases was between 1 and 3 days. The multivariate model results show that the three following factors were critical influencing factors: nationality was foreign nationality (P = 0.037), results of initial nucleic acid detection were negative (P = 0.000) and the interval between entering mainland China and the detection of positive results (T) exceeded two days (P = 0.008).ConclusionThe results suggested that all travelers and returning resident should be taken strict sampling and testing, and isolation measures, improved the accuracy of the initial nucleic acid test results, and the detection efficiency and shortening the interval between entering mainland China and detection of positive results.

New problems and countermeasures in the prevention and control of COVID-19

New problems and countermeasures in the prevention and control of COVID-19

High concentrations of hypochlorous acid-based disinfectant in the environment reduced the load of SARS-CoV-2 in nucleic acid amplification testing.

During the severe acute respiratory syndrome coronavirus type 2 (SARS‐CoV‐2) pandemic, chlorine‐containing disinfectants have been widely used in nucleic acid amplification testing laboratories. Whether the use of disinfectants affect the results of viral nucleic acid amplification is unknown. We examined the impact of different hypochlorous acid (HOCl) concentrations on the quantitative results of SARS‐CoV‐2 by real‐time reverse‐transcription polymerase chain reaction (RT‐PCR). We also explored the mechanisms and models of action of chlorine‐containing disinfectants that affected the detection of SARS‐CoV‐2. The results showed that different HOCl concentrations and different action times had an impact on the SARS‐CoV‐2 results. High concentrations of ambient HOCl have a greater impact than low concentrations, and this effect will increase with the extension of the action time and with the increase in ambient humidity. Compared with the enzymes or the extracted RNA required for RT‐PCR, the impact of HOCl on the SARS‐CoV‐2 detection is more likely to be caused by damage to primers and probes in the PCR system. The false negative result still existed after changing the ambient disinfectant to ethanol but not peracetic acid. The use of HOCl in the environment will have an unpredictable impact on the nucleic acid test results of SARS‐CoV‐2. In order to reduce the possibility of false negative of SARS‐CoV‐2 nucleic acid test and prevent the spread of epidemic disease, environmental disinfectants should be used at the beginning and end of the experiment rather than during the experimental operation.

Influenza colloidal gold method and blood routine tests combination for rapid diagnosis of influenza: a decision tree-based analysis

Rapid influenza diagnosis can facilitate targeted treatment and reduce antibiotic misuse. However, diagnosis efficacy remains unclear. This study examined the efficacy of a colloidal gold rapid test for rapid influenza diagnosis. Clinical characteristics of 520 patients with influenza-like illness presenting at a fever outpatient clinic during two influenza seasons (2017–2018; 2018–2019) were evaluated. The clinical manifestations and results of routine blood, colloidal gold, and nucleic acid tests were used to construct a decision tree with three layers, nine nodes, and five terminal nodes. The combined positive predictive value of a positive colloidal gold test result and monocyte level within 10.95–12.55% was 88.2%. The combined negative predictive value of a negative colloidal gold test result and white blood cell count > 9.075 × 109/L was 84.9%. The decision-tree model showed the satisfactory accuracy of an early influenza diagnosis based on colloidal gold and routine blood test results.

Study of Laboratory Parameters in COVID-19 Patients at a Tertiary Care Teaching Hospital in Uttar Pradesh

Introduction: COVID-19 infection has been affecting vast population all over the world since 2019. It is very important to make optimum use of routine laboratory parameters in evaluating severity of COVID-19 disease. This will help the clinicians to improve allocation of technical human resources to patients who require it the most. During the path of the COVID-19 disease, inflammatory indices such as lactate dehydrogenase (LDH), C-reactive protein (CRP), interleukin-6 (IL-6), biomarkers like serum procalcitonin (PCT), and ferritin and indices of coagulation profile like D-Dimer, PT levels, and hematological parameters like total leukocyte count, platelets carry prognostic value. The objective of the study is to estimate the utility of various laboratory Biochemical and Hematological parameters in COVID-19 disease. Materials and Methods: The present study is a retrospective cross-sectional observational study conducted in tertiary care rural teaching hospital. The study was conducted from September 1, 2020, to January 31, 2021. The study was carried out on the patients who were hospitalized in Isolation Ward and COVID ICU in our L3 COVID hospital. All patients with positive SARS-CoV-2 nucleic acid test results were included in the study. A sample size of 310 patients was taken. The basic demographic details were collected from the admission records. The confirmatory test for SARS-CoV-2 was done using the WHO-approved kits based on real-time reverse transcription polymerase chain reaction for which suspected cases underwent nasopharyngeal/oropharyngeal swab testing. The levels of CRP, IL-6, PCT, ferritin LDH, D-dimer, complete blood counts, PT were based on standardized methods obtained using various biochemical and hematological laboratory analyzers. Data of investigation reports were gathered from electronic patient record system. Statistical analysis was performed using the Statistical Package for the Social Sciences for Windows (version 25.0). Results: Our study clearly shows that levels of IL-6, D Dimer, PT, and LDH are quite significantly raised in majority of patients while PCT and ferritin being somewhat nonspecific show an increase but not to that significant numbers. The hematological parameters show levels which indicate mild anemia, leukocytosis, neutrophilia, lymphopenia, and thrombocytopenia in patients infected with COVID-19 disease. Conclusion: COVID-19 is an unexplored, new entity with a sudden worldwide onset. The medical fraternity is yet to conquer and analyse this novel virus.

Efficacy and safety of ReDuNing injection as a treatment for COVID-19 and its inhibitory effect against SARS-CoV-2

BackgroundAlthough the rapid emergence of coronavirus disease 2019 (COVID-19) poses a considerable threat to global public health, no specific treatment is available for COVID-19. ReDuNing injection (RDN) is a traditional Chinese medicine known to exert antibacterial, antiviral, antipyretic, and anti-inflammatory effects. In addition, RDN has been recommended in the diagnosis and treatment of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-associated pneumonia by the National Health Council and the National Administration of Chinese Medicine. However, there is no information regarding its efficacy against COVID-19. Aim of studyThis study was designed to determine the clinical efficacy of RDN in patients with COVID-19 and characterize its antiviral activity against SARS-CoV-2 in vitro. Materials and methodsA total of 50 adults with COVID-19 were included in this study, and the primary endpoint was recovery from clinical symptoms following 14 days of treatment. General improvements were defined as the disappearance of the major symptoms of infection including fever, fatigue, and cough. The secondary endpoints included the proportion of patients who achieved clinical symptom amelioration on days 7 and 10, time to clinical recovery, time to a negative nucleic acid test result, duration of hospitalization, and time to defervescence. Plaque reduction and cytopathic effect assays were also performed in vitro, and reverse-transcription quantitative PCR was performed to evaluate the expression of inflammatory cytokines (TNF-α, IP-10, MCP-1, IL-6, IFN-α, IFN-γ, IL-2 and CCL-5) during SARS-CoV-2 infection. ResultsThe RDN group exhibited a shorter median time for the resolution of clinical symptoms (120 vs. 220 h, P < 0.0001), less time to a negative PCR test result (215 vs. 310 h, P = 0.0017), shorter hospitalization (14.8 vs. 18.5 days, P = 0.0002), and lower timeframe for defervescence (24.5 vs. 75 h, P = 0.0001) than the control group. In addition, time to improved imaging was also shorter in the RDN group than in the control group (6 vs.8.9 days, P = 0.0273); symptom resolution rates were higher in the RDN group than in the control group at 7 (96.30% vs. 39.13%, P < 0.0001) and 10 days (96.30% vs. 56.52%, P = 0.0008). No allergic reactions or anaphylactic responses were reported in this trial. RDN markedly inhibited SARS-CoV-2 proliferation and viral plaque formation in vitro. In addition, RDN significantly reduced inflammatory cytokine production in infected cells. ConclusionsRDN relieves clinical symptoms in patients with COVID-19 and reduces SARS-CoV-2 infection by regulating inflammatory cytokine-related disorders, suggestion that this medication might be a safe and effective treatment for COVID-19.

Continued nucleic acid tests for SARS-CoV-2 following discharge of patients with COVID-19 in Lu'an, China.

BackgroundStudies have shown that discharged Coronavirus disease 2019 (COVID-19) patients have retested positive for SARS-CoV-2 during a follow-up RT-PCR test. We sought to assess the results of continued nucleic acid testing for SARS-CoV-2 patients in COVID-19 patients after they were discharged in Lu’an, China.MethodsWe conducted RT-PCR tests on sputum, throat swabs, fecal or anal swabs, and urine samples collected from 67 COVID-19 patients following discharge. Samples were collected on the 7th and 14th days following discharge. Patients testing positive on the 7th or 14th day were retested after 24 hours until they tested negative twice.ResultsSeventeen (17/67, 25.4%) discharged COVID-19 patients had a positive RT-PCR retest for SARS-CoV-2. Among them, 14 (82.4%) were sputum positive, five (29.4%) were throat swab positive, seven (41.2%) were fecal or anal swab positive, one (5.9%) was urine sample positive, five (29.4%) were both sputum and throat swab positive, four (23.5%) were both sputum and fecal test positive, and one (5.9%) was positive of all four specimens. The shortest period of time between discharge and the last positive test was 7 days, the longest was 48 days, and the median was 16 days. The proportion of positive fecal or anal swab tests increased from the third week. The median Cq cut-off values after onset were 26.7 after the first week, 37.7 the second to sixth week, and 40 after the sixth week. There were no significant differences between the RT-PCR retest positive group and the unrecovered positive group.ConclusionsThere was a high proportion of patients who retested positive for COVID-19. Discharge criteria have remained fairly consistent so we encourage regions affected by COVID-19 to appropriately amend their current criteria.

Application of anti-HCV and HCV RNA detection in intravenous drug users

Objective: To explore the diagnostic value of anti-HCV and HCV RNA so as to provide an accurate and efficient detection strategy for the diagnosis of HCV in intravenous drug users. Methods: 527 plasma samples from intravenous drug users were collected, and preliminary anti-HCV ELISA screening test was performed. A recombinant immunoblot assay (RIBA) was used as confirmatory assay for reactive antibody samples. All samples were tested for HCV RNA, followed by analysis of anti-HCV screening test, RIBA and HCV nucleic acid test results. Results: Anti-HCV ELISA results were reactive in 386 out of 527 intravenous drug users and non-reactive in 141. Among the 386 reactive antibody samples detected by RIBA, 370 cases were anti-HCV positive, 6 cases were anti-HCV indeterminate and 10 cases were anti-HCV negative. Anti-HCV ELISA and RIBA positive coincidence detection rate was 95.85% (370/386), and 70.21% (370/527) among intravenous drug users. HCV RNA was negative in all 10 anti-HCV RIBA non-reactive samples. 376 anti-HCV RIBA-positive and indeterminate samples were tested for HCV RNA, of which 56.93% (300/527) were current HCV infection, and 14.42% (76/527) were past HCV infection. Among 141 anti-HCV ELISA negative samples, the residual risk by anti-HCV ELISA screening for HCV RNA was 1.52% (8/527). HCV viral load distribution among intravenous drug users showed that the high viral load value (>10(7) IU/ml) and low viral load values (< 10(2) IU/ml) accounted for 1.95% and 2.27%, respectively, while the samples with viral load value of 1×10(2) ~ 1×10(7) IU/ mL accounted for 95.78% (295/308), and were mainly distributed in 1×10(5) ~ 1×10(6) IU/ml (37.99%). ELISA + RIBA + NAT assay detection strategies had differentiated 300 cases of current HCV infection, 76 cases of past HCV infection and 10 cases of false positive anti-HCV results, while ELISA+NAT assay detection strategies had only detected 300 cases of current HCV infection. However, of the 386 positive subjects screened for antibodies, 10 (2.59%) were undifferentiated false positives. Conclusion: Intravenous drug users are the high-risk population of HCV infection with high prevalence and high viral load. Anti-HCV screening for intravenous drug users will have a certain degree of residual risk. Therefore, anti-HCV ELISA screening and nucleic acid detection strategy can accurately diagnose the current infected patients; however, it cannot distinguish the false positive results of antibody screening.

Clinical course and management of 73 hospitalized moderate patients with COVID-19 outside Wuhan.

Moderate cases account for the majority in hospitalized patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and can also progress to severe/critical condition. Here, we investigated the clinical course and management of hospitalized moderate SARS-CoV-2 patients. The medical records and follow-up data were analyzed from the SARS-CoV-2 patients outside Wuhan. A total of 73 moderate patients (38 men, 35 women) were included, with median age of 47.0 (38.5–57.5) years. Among them, only one patient (1.4%) died using active treatment to improve symptoms. The median duration of the four main symptoms cough, fever, chest tightness, and fatigue were 11.0, 8.0, 11.0, and 7.0 days, respectively; the median duration of the positive nucleic acid test (NAT) results for SARS-CoV-2 was 16.5 days; the median hospitalization time was 25.0 days in 72 moderate survivors. The duration of cough and fever was positively correlated with the duration of the positive NAT results. On admission, 50% had lymphopenia; less than 30% had abnormal blood biochemistry findings involving hyperglycemia, liver function and myocardial enzymes. At discharge, the laboratory indexes were substantially improved. Two weeks after discharge, 5.6% survivors experienced a recurrence of the positive NAT results. Moderate SARS-CoV-2 patients have a good prognosis by the active treatment. A small proportion of the recovered moderate patients still may be virus carriers and require an additional round of viral detection.

The effect of refined nursing intervention on patients undergoing maintenance hemodialysis in the hemodialysis center during the COVID-19 epidemic

BackgroundThe outbreak of novel coronavirus pneumonia has exerted considerable psychological pressure on patients undergoing hemodialysis, resulting in unhealthy psychological emotions. Therefore, it is of great significance to carry out strict management and refined nursing intervention for patients undergoing maintenance hemodialysis during the prevention and control of novel coronavirus. This study aims to analyze and discuss the effect of clinical refined nursing intervention on patients undergoing maintenance hemodialysis during the coronavirus disease 2019 (COVID-19) epidemic.MethodsThis was a prospective cohort study. In this study, we used the Symptom Checklist-90 (SCL-90) or the Chinese adult SCL-90 norm to conduct nursing interventions for patients undergoing maintenance hemodialysis to investigate the effect of clinical refined nursing intervention on patients undergoing maintenance hemodialysis during the COVID-19 epidemic.ResultsThe scores for all the factors of SCL-90 of patients undergoing maintenance hemodialysis were higher than those of the Chinese SCL-90, and patients with a single factor score ≥ 2 had a higher level of depression and anxiety, with extremely significant difference (p < 0.01). The depression and anxiety of the patients were reduced after the intervention, and there was a statistical difference. Among the 172 patients, the results of both nucleic acid tests were negative.ConclusionDuring the COVID-19 epidemic, providing patients undergoing maintenance hemodialysis with refined nursing intervention can regulate negative emotions, reduce related complications, improve their quality of life, and improve the nurse–patient relationship.

Clinical Significance of an IgM and IgG Test for Diagnosis of Highly Suspected COVID-19.

Background: Nucleic acid detection and CT scanning have been reported in COVID-19 diagnosis. Here, we aimed to investigate the clinical significance of IgM and IgG testing for the diagnosis of highly suspected COVID-19.Methods: A total of 63 patients with suspected COVID-19 were observed, 57 of whom were enrolled (24 males and 33 females). The selection was based on the diagnosis and treatment protocol for COVID-19 (trial Sixth Edition) released by the National Health Commission of the People's Republic of China. Patients were divided into positive and negative groups according to the first nucleic acid results from pharyngeal swab tests. Routine blood tests were detected on the second day after each patient was hospitalized. The remaining serum samples were used for detection of novel coronavirus-specific IgM/IgG antibodies.Results: The rate of COVID-19 nucleic acid positivity was 42.10%. The positive detection rates with a combination of IgM and IgG testing for patients with COVID-19 negative and positive nucleic acid test results were 72.73 and 87.50%, respectively.Conclusions: We report a rapid, simple, and accurate detection method for patients with suspected COVID-19 and for on-site screening for close contacts within the population. IgM and IgG antibody detection can identify COVID-19 after a negative nucleic acid test. Diagnostic accuracy of COVID-19 might be improved by nucleic acid testing in patients with a history of epidemic disease or with clinical symptoms, as well as CT scans when necessary, and serum-specific IgM and IgG antibody testing after the window period.

Diagnosis and Treatment Protocol for COVID-19 Patients (Tentative 8th Edition): Interpretation of Updated Key Points.

Diagnosis and Treatment Protocol for COVID-19 Patients (Tentative 8th Edition): Interpretation of Updated Key Points.

Spatial technologies to strengthen traditional testing for SARS-CoV-2.

Advanced spatial and digital technologies may help us to take fuller advantage of limited testing resources to monitor the infection status of a large population in a cost-effective manner. Moreover, they may provide additional evidence to supplement results of nucleic acid testing (NAT) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to decrease false-negative and false-positive rates.

Research study on nucleic acid testing of hemostatic stickers used and the surface of the recipients' hands after the inoculation of inactivated SARS-CoV-2 vaccine

Among the staff of Beijing Chao-Yang Hospital, Capital Medical University, who received the inactivated SARS-CoV-2 vaccine on January 30 in 2021, 28 recipients were selected for this research. Samples for nucleic acid tests were collected from the surface of the recipients' both hands before and after vaccination. The hemostatic stickers used after the inoculation were also collected for nucleic acid tests. The nucleic acid tests of the samples collected from the surface of both hands of the 28 recipients before vaccination were all negative. After vaccination, the nucleic acid tests of the samples collected from the surface of both hands of recipients were positive in 3 cases, and suspicious in 8 cases, with a positive rate of 10.7%. A total of 25 hemostatic stickers used were collected, 24 of them had positive nucleic acid tests, and the rest one had suspicious nucleic acid test result, with a positive rate of 96%. The hemostatic stickers used after the inoculation have the risk of nucleic acid contamination.

Clinical analysis of seven pediatric patients with coronavirus disease 2019 (COVID-19) in Jingzhou, Hubei, China: a retrospective study.

BackgroundThe novel coronavirus disease 2019 (COVID-19) epidemic has spread globally, along with its incidence among children. The purpose of this study was to evaluate the clinical characteristics and outcomes of children infected with COVID-19 and to provide a reference for clinical work.MethodsThe study retrospectively reviewed the clinical characteristics and prognosis of 7 children diagnosed with COVID-19 infection at The First People’s Hospital of Jingzhou between January 30 and February 29, 2020.ResultsOf the 7 cases, 2 were male and 5 were female, aged 3 months and 14 days to 12 years old (median age 3 years old). There was 1 asymptomatic carrier, 5 cases with mild type infection, which had the main symptoms of cough (4/5) and fever (4/5), and 1 case of moderate type. Among the 7 cases, serum white blood cell count was increased in 1 case, decreased in 1 case, liver transaminase was increased in 1 case, lactate dehydrogenase was increased in 3 cases, creatine kinase MB (CK-MB) was increased in 2 cases, and C-reactive protein was elevated in 2 cases. A total of 4 cases were complicated with mycoplasma pneumoniae and/or influenza B virus infection. A single case of chest computed tomography (CT) showed viral pneumonia. With routine antiviral and symptomatic support therapy, the median time taken for the results of nucleic acid testing by pharyngeal swab to become negative was 14 days (6–26 days) and the median hospital stay was 15 days (8–31 days). All participants were cured and subsequently discharged from hospital. Only 1 case was positive for nucleic acid testing by pharyngeal swab 1 month after being discharged, and the anal swab of 1 case for nucleic acid testing was positive 2 months after being discharged.ConclusionsAll children with COVID-19 who were included in this study in Jingzhou were infected via family clustering, and the laboratory examinations were not specific. Fever and cough were common symptoms, but all cases were mild and had good prognoses.

A deep learning algorithm using CT images to screen for Corona virus disease (COVID-19)

ObjectiveThe outbreak of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-COV-2) has caused more than 26 million cases of Corona virus disease (COVID-19) in the world so far. To control the spread of the disease, screening large numbers of suspected cases for appropriate quarantine and treatment are a priority. Pathogenic laboratory testing is typically the gold standard, but it bears the burden of significant false negativity, adding to the urgent need of alternative diagnostic methods to combat the disease. Based on COVID-19 radiographic changes in CT images, this study hypothesized that artificial intelligence methods might be able to extract specific graphical features of COVID-19 and provide a clinical diagnosis ahead of the pathogenic test, thus saving critical time for disease control.MethodsWe collected 1065 CT images of pathogen-confirmed COVID-19 cases along with those previously diagnosed with typical viral pneumonia. We modified the inception transfer-learning model to establish the algorithm, followed by internal and external validation.ResultsThe internal validation achieved a total accuracy of 89.5% with a specificity of 0.88 and sensitivity of 0.87. The external testing dataset showed a total accuracy of 79.3% with a specificity of 0.83 and sensitivity of 0.67. In addition, in 54 COVID-19 images, the first two nucleic acid test results were negative, and 46 were predicted as COVID-19 positive by the algorithm, with an accuracy of 85.2%.ConclusionThese results demonstrate the proof-of-principle for using artificial intelligence to extract radiological features for timely and accurate COVID-19 diagnosis.Key Points• The study evaluated the diagnostic performance of a deep learning algorithm using CT images to screen for COVID-19 during the influenza season.• As a screening method, our model achieved a relatively high sensitivity on internal and external CT image datasets.• The model was used to distinguish between COVID-19 and other typical viral pneumonia, both of which have quite similar radiologic characteristics.

Detection of SARS-CoV-2 in fecal samples with different pretreatment methods and PCR kits

BackgroundGastrointestinal symptoms are common in COVID-19 patients and SARS-CoV-2 RNA has been detected in the patients’ feces, which could lead to fecal–oral transmission. Therefore, fecal sample testing with real-time RT-PCR is highly recommended as a routine test for SARS-CoV-2 infection. However, varying rates of detection in fecal sample have been reported. The aim of this study was to provide insights into the detection rates of SARS-CoV-2 in COVID-19 patients’ fecal sample by using four real-time RT-PCR kits and two pretreatment methods (inactive and non-inactive).ResultsThe detection rate of Trizol pretreatment group was slightly higher than that of Phosphate Buffered Saline (PBS) groups, showing that pretreatment and inactivation by Trizol had no influence to SARS-CoV-2 nucleic acid test (NAT) results. 39.29% detection rate in fecal sample by DAAN was obtained, while Bio-germ was 40.48%, Sansure 34.52%, and GeneoDx 33.33%. The former three kits had no significant difference. The DAAN kit detection rates of ORF1ab and N gene were nearly equal and Ct value distribution was more scattered, while the Bio-germ kit distribution was more clustered. The positive rate of SARS-COV-2 in fecal samples correlated with the severity of the disease, specifically, severe cases were less likely to be identified than asymptomatic infection in the DAAN group (adjusted OR 0.05, 95%CI = 0.00 ~ 0.91).ConclusionsTrizol should be of choice as a valid and safe method for pretreatment of fecal samples of SARS-CoV-2. All real-time RT-PCR kits assessed in this study can be used for routine detection of SARS-CoV-2 in fecal samples. While DAAN, with high NAT positive rate, could be the best out of the 4 kits used in this study. SARS-CoV-2 positive rate in fecal sample was related to the severity of illness.

Clinical characteristics of discharged COVID‑19 patients with reappeared positive nucleic acid test

Objective: To investigate the incidence of reappearance of positive results of nucleic acid (NA) test in discharged COVID‑19 patients, and retrospectively evaluate and compare the clinical characteristics between reappeared NA‑positive group and NA‑negative group, so as to provide the decision‑making basis for the quarantine management, health monitoring, and epidemic prevention. Methods: A total of 188 cases of discharged COVID‑19 patients from 3 quarantine observation sites in Wuhan from February to March 2020 were divided into reappeared NA‑positive group and NA‑negative group, based on the NA test. Clinical characteristics including general information, symptoms, underlying diseases, severity of disease, steroid administration, duration of hospitalization, duration from the beginning of positive to negative and time of onset of reappearance of positive for NA test, were compared between the two groups. Results: Of the 188 cases, 30 cases (15.96%) reappeared positive for NA test, and onset of reappearance ranged from day 1 to day 16 since the last NA negative, with a median time of 5 days after onset. A total of 51 cases (32.28%) in NA‑negative group had underlying diseases, while 18 (60.0%) cases reappeared NA‑positive had underlying diseases, and the rate of underlying diseases showed significant difference between the two groups (P<0.01). However, there were no statistical differences in gender, age, and symptoms on admission, severity of disease, steroid administration, duration from the beginning of positive to negative for NA test between the two groups. Conclusion: Since COVID‑19 patients with underlying diseases showed higher incidence of reappearance of positive NA test, COVID‑19 patients after discharge need to strengthen for quarantine control, further continuous health monitoring, and re‑tests of SARS‑CoV‑2 nucleic acid. © 2021, Editorial Board of Medical Journal of Wuhan University. All right reserved.

Clinical characteristics and viral shedding kinetics of 38 asymptomatic patients with coronavirus disease 2019: A retrospective observational study.

This study aims to investigate the clinical characteristics and viral shedding kinetics of asymptomatic patients with coronavirus disease 2019 (COVID-19).The data of 38 asymptomatic patients positive for SARS-CoV-2 nucleic acid were collected from February to March 2020 in Tuanfeng County, Huanggang, Hubei, China. The epidemiology, laboratory examination, chest imaging, viral nucleic acid test results, clinical characteristics, and viral shedding time were summarized in this retrospective study.The study included 20 family members of patients with COVID-19, 10 medical personnel participating in COVID-19 treatment or working in a fever clinic, 6 personnel from quarantine places, 1 individual with a close contact history with confirmed patients, and 1 local epidemic prevention personnel. All were positive for SARS-CoV-2 nucleic acid. The white blood cell (WBC) count, the absolute value of lymphocytes, C-reactive protein (CRP), and D-dimer were normal. Pneumonia manifestations were not found in the chest computed tomography (CT) scan of 36 patients; the remaining 2 cases included a 1-year-old child and a pregnant woman, and they did not undergo chest CT. The viral shedding time was 6 days.All asymptomatic patients with COVID-19 had a history of close contact or exposure. Laboratory tests were normal. Chest imaging did not show any pneumonia manifestation. The viral shedding time was <10 days, which is shorter than that of patients with COVID-19. A timely discovery of such asymptomatic infections is crucial for blocking the spread of the virus and strengthening the prevention and control measures.