scholarly journals Monitoring and predicting viral dynamics in SARS-CoV-2-infected Patients

2020 ◽  
Author(s):  
Shaoqing Wen ◽  
Jianxue Xiong ◽  
Chang Sun ◽  
Barnaby Edward Young ◽  
David Chien Lye ◽  
...  
Keyword(s):  
Throat Swab ◽  
False Negative ◽  
Viral Dynamics ◽  
Test Results ◽  
Rt Pcr ◽  
Time Model ◽  
Viral Loads ◽  
Robust Model ◽  
Health Situation ◽  
The Mathematical Model

AbstractThis study is based on the a simple but robust model we developed urgently to accurately monitor and predict viral dynamics for each SARS-CoV-2-infected patient, given the limited number of RT-PCR tests and the complexity of each individual’s physical health situation. We used the mathematical model to monitor and predict the changes of viral loads from different nasal and throat swab of clinical specimens collected from diagnosed patients. We also tested this real-time model by using the data from the SARS-CoV-2-infected patients with different severity. By using this model (http://58.87.113.187:8080/), we can predict the viral dynamics of patients, minimize false-negative test results, and screen the patients who are at risk of testing positive again after recovery. We sincerely thank those who are on the front lines battling SARS-CoV-2 virus. We hope this model will be useful for SARS-CoV-2-infected patients.

scholarly journals Microfluidic Nano-Scale qPCR Enables Ultra-Sensitive and Quantitative Detection of SARS-CoV-2

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1425
Author(s):  
Xin Xie ◽  
Tamara Gjorgjieva ◽  
Zaynoun Attieh ◽  
Mame Massar Dieng ◽  
Marc Arnoux ◽  
...  
Keyword(s):  
Viral Infections ◽  
Limit Of Detection ◽  
False Negative ◽  
False Negative Rate ◽  
Clinical Samples ◽  
Quantitative Detection ◽  
Rt Pcr ◽  
Viral Loads ◽  
Nano Scale ◽  
Negative Rate

A major challenge in controlling the COVID-19 pandemic is the high false-negative rate of the commonly used RT-PCR methods for SARS-CoV-2 detection in clinical samples. Accurate detection is particularly challenging in samples with low viral loads that are below the limit of detection (LoD) of standard one- or two-step RT-PCR methods. In this study, we implemented a three-step approach for SARS-CoV-2 detection and quantification that employs reverse transcription, targeted cDNA preamplification, and nano-scale qPCR based on a commercially available microfluidic chip. Using SARS-CoV-2 synthetic RNA and plasmid controls, we demonstrate that the addition of a preamplification step enhances the LoD of this microfluidic RT-qPCR by 1000-fold, enabling detection below 1 copy/µL. We applied this method to analyze 182 clinical NP swab samples previously diagnosed using a standard RT-qPCR protocol (91 positive, 91 negative) and demonstrate reproducible and quantitative detection of SARS-CoV-2 over five orders of magnitude (<1 to 106 viral copies/µL). Crucially, we detect SARS-CoV-2 with relatively low viral load estimates (<1 to 40 viral copies/µL) in 17 samples with negative clinical diagnosis, indicating a potential false-negative rate of 18.7% by clinical diagnostic procedures. In summary, this three-step nano-scale RT-qPCR method can robustly detect SARS-CoV-2 in samples with relatively low viral loads (<1 viral copy/µL) and has the potential to reduce the false-negative rate of standard RT-PCR-based diagnostic tests for SARS-CoV-2 and other viral infections.

scholarly journals Insufficient Sensitivity of RNA Dependent RNA Polymerase Gene of SARS-CoV-2 Viral Genome as Confirmatory Test using Korean COVID-19 Cases

2020 ◽  
Author(s):  
Soyoun Kim ◽  
Dong-Min Kim ◽  
Baeckseung Lee
Keyword(s):  
Diagnostic Methods ◽  
Confirmatory Test ◽  
Test Results ◽  
Rt Pcr ◽  
Viral Loads ◽  
Asymptomatic Patients ◽  
Pcr Method ◽  
Who Guideline ◽  
Rna Polymerase Gene ◽  
Insufficient Sensitivity

Since mid-December of 2019, coronavirus disease 2019 (COVID-19) has been spreading from Wuhan, China. As of February 21, total 75,773 confirmed cases worldwide have spread to more than two dozen countries. Transmission of COVID-19 can occur early in the course of infection since SARS-CoV-2 viral loads in asymptomatic patients are similar to that in the symptomatic patients. Therefore, more sensitive diagnostic methods are needed to detect early phase of the infection to prevent secondary or tertiary spreads. Here, we compare the RT-PCR confirmatory test results using two different SARS-CoV-2 viral RNAs from two Korean COVID-19 confirmed cases.RT-PCR method targeting the RdRP gene, which was recommended by WHO guideline, was less sensitive than targeting N genes (as per CDC guideline). Because many countries follow the WHO guideline, our findings may contribute to the early diagnosis of COVID-19.

scholarly journals SARS-CoV2 Testing: The Limit of Detection Matters

2020 ◽  
Author(s):  
Ramy Arnaout ◽  
Rose A. Lee ◽  
Ghee Rye Lee ◽  
Cody Callahan ◽  
Christina F. Yen ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Diagnostic Testing ◽  
False Negative ◽  
False Negative Rate ◽  
Fold Increase ◽  
Test Results ◽  
Rt Pcr ◽  
False Negatives ◽  
Healthcare Network ◽  
Negative Rate

AbstractResolving the COVID-19 pandemic requires diagnostic testing to determine which individuals are infected and which are not. The current gold standard is to perform RT-PCR on nasopharyngeal samples. Best-in-class assays demonstrate a limit of detection (LoD) of ~100 copies of viral RNA per milliliter of transport media. However, LoDs of currently approved assays vary over 10,000-fold. Assays with higher LoDs will miss more infected patients, resulting in more false negatives. However, the false-negative rate for a given LoD remains unknown. Here we address this question using over 27,500 test results for patients from across our healthcare network tested using the Abbott RealTime SARS-CoV-2 EUA. These results suggest that each 10-fold increase in LoD is expected to increase the false negative rate by 13%, missing an additional one in eight infected patients. The highest LoDs on the market will miss a majority of infected patients, with false negative rates as high as 70%. These results suggest that choice of assay has meaningful clinical and epidemiological consequences. The limit of detection matters.

scholarly journals Evaluation of the SARS-CoV-2 positivity ratio and upper respiratory tract viral load among asymptomatic individuals screened before hospitalization or surgery in Flanders, Belgium

PLoS ONE ◽  
2021 ◽  
Vol 16 (11) ◽  
pp. e0259908
Author(s):  
Laura Heireman ◽  
Steven Abrams ◽  
Peggy Bruynseels ◽  
Reinoud Cartuyvels ◽  
Lize Cuypers ◽  
...  
Keyword(s):  
Viral Load ◽  
Respiratory Tract ◽  
Age Group ◽  
Test Results ◽  
Rt Pcr ◽  
Median Viral Load ◽  
Viral Loads ◽  
Asymptomatic Patients ◽  
Positivity Ratio ◽  
Second Wave

Introduction The incidence of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infections in the Belgian community is mainly estimated based on test results of patients with coronavirus disease (COVID-19)-like symptoms. The aim of this study was to investigate the evolution of the SARS-CoV-2 reverse transcriptase polymerase chain reaction (RT-PCR) positivity ratio and distribution of viral loads within a cohort of asymptomatic patients screened prior hospitalization or surgery, stratified by age category. Materials/Methods We retrospectively studied data on SARS-CoV-2 real-time RT-PCR detection in respiratory tract samples of asymptomatic patients screened pre-hospitalization or pre-surgery in nine Belgian hospitals located in Flanders over a 12-month period (1 April 2020–31 March 2021). Results In total, 255925 SARS-CoV-2 RT-PCR test results and 2421 positive results for which a viral load was reported, were included in this study. An unweighted overall SARS-CoV-2 real-time RT-PCR positivity ratio of 1.27% was observed with strong spatiotemporal differences. SARS-CoV-2 circulated predominantly in 80+ year old individuals across all time periods except between the first and second COVID-19 wave and in 20–30 year old individuals before the second COVID-19 wave. In contrast to the first wave, a significantly higher positivity ratio was observed for the 20–40 age group in addition to the 80+ age group compared to the other age groups during the second wave. The median viral load follows a similar temporal evolution as the positivity rate with an increase ahead of the second wave and highest viral loads observed for 80+ year old individuals. Conclusion There was a high SARS-CoV-2 circulation among asymptomatic patients with a predominance and highest viral loads observed in the elderly. Moreover, ahead of the second COVID-19 wave an increase in median viral load was noted with the highest overall positivity ratio observed in 20–30 year old individuals, indicating they could have been the hidden drivers of this wave.

scholarly journals SARS-CoV-2 Reinfection: A Case Series from a 12-Month Longitudinal Occupational Cohort

2021 ◽  
Author(s):  
Christina D Mack ◽  
Caroline Tai ◽  
Robby Sikka ◽  
Yonatan H Grad ◽  
Lisa L Maragakis ◽  
...  
Keyword(s):  
Immune Response ◽  
Clinical Presentation ◽  
Case Series ◽  
Antibody Test ◽  
Genomic Sequencing ◽  
Viral Dynamics ◽  
Test Results ◽  
Rt Pcr ◽  
Occupational Cohort

Abstract Seven cases of COVID-19 SARS-CoV-2 reinfection from the NBA 2020-2021 occupational testing cohort are described including clinical details, antibody test results, genomic sequencing, and longitudinal RT-PCR results. Reinfections were infrequent and varied in clinical presentation, viral dynamics, and immune response.

scholarly journals Potential False-Negative Nucleic Acid Testing Results for Severe Acute Respiratory Syndrome Coronavirus 2 from Thermal Inactivation of Samples with Low Viral Loads

2020 ◽  
Vol 66 (6) ◽  
pp. 794-801 ◽  
Author(s):  
Yang Pan ◽  
Luyao Long ◽  
Daitao Zhang ◽  
Tingting Yuan ◽  
Shujuan Cui ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Severe Acute Respiratory Syndrome ◽  
Thermal Inactivation ◽  
Rna Virus ◽  
False Negative ◽  
Heat Inactivation ◽  
Nucleic Acid Testing ◽  
Rt Pcr ◽  
False Negatives ◽  
Viral Loads

Abstract Background Coronavirus disease-2019 (COVID-19) has spread widely throughout the world since the end of 2019. Nucleic acid testing (NAT) has played an important role in patient diagnosis and management of COVID-19. In some circumstances, thermal inactivation at 56°C has been recommended to inactivate severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) before NAT. However, this procedure could theoretically disrupt nucleic acid integrity of this single-stranded RNA virus and cause false negatives in real-time polymerase chain reaction (RT-PCR) tests. Methods We investigated whether thermal inactivation could affect the results of viral NAT. We examined the effects of thermal inactivation on the quantitative RT-PCR results of SARS-CoV-2, particularly with regard to the rates of false-negative results for specimens carrying low viral loads. We additionally investigated the effects of different specimen types, sample preservation times, and a chemical inactivation approach on NAT. Results Our study showed increased Ct values in specimens from diagnosed COVID-19 patients in RT-PCR tests after thermal incubation. Moreover, about half of the weak-positive samples (7 of 15 samples, 46.7%) were RT-PCR negative after heat inactivation in at least one parallel testing. The use of guanidinium-based lysis for preservation of these specimens had a smaller impact on RT-PCR results with fewer false negatives (2 of 15 samples, 13.3%) and significantly less increase in Ct values than heat inactivation. Conclusion Thermal inactivation adversely affected the efficiency of RT-PCR for SARS-CoV-2 detection. Given the limited applicability associated with chemical inactivators, other approaches to ensure the overall protection of laboratory personnel need consideration.

scholarly journals Coronavirus Disease 2019 (COVID-19) Candidate Chest CT Features: A Systematic Review of Extracted Imaging Features from 7571 Individuals

2020 ◽  
Author(s):  
Javad Zahiri ◽  
Mohammad Hossein Afsharinia ◽  
Zhaleh Hekmati ◽  
Mohsen Khodarahmi ◽  
Shahrzad Hekmati ◽  
...  
Keyword(s):  
False Negative ◽  
Ct Imaging ◽  
Response To Therapy ◽  
Imaging Features ◽  
Lung Involvement ◽  
Test Results ◽  
Rt Pcr ◽  
Pubmed Database ◽  
Bilateral Lung ◽  
Pcr Test

AbstractSince the outbreak of Coronavirus Disease 2019 (COVID-19) causing novel coronavirus (2019-nCoV)-infected pneumonia (NCIP), over 45 million affected cases have been reported worldwide. Many patients with COVID-19 have involvement of their respiratory system. According to studies in the radiology literature, chest computed tomography (CT) is recommended in suspected cases for initial detection, evaluating the disease progression and monitoring the response to therapy. The aim of this article is to review the most frequently reported imaging features in COVID-19 patients in order to provide a reliable insight into expected CT imaging manifestations in patients with positive reverse-transcription polymerase chain reaction (RT-PCR) test results, and also for the initial detection of patients with suspicious clinical presentation whose RT-PCR test results are false negative. A total of 60 out of 173 initial COVID-19 studies, comprising 7571 individuals, were identified by searching PubMed database for articles published between the months of January and June 2020. The data of these studies were related to patients from China, Japan, Italy, USA, Iran and Singapore. Among 40 reported features, presence of ground glass opacities (GGO), consolidation, bilateral lung involvement and peripheral distribution are the most frequently observed ones, reported in 100%, 91.7%, 85%, and 83.3% of articles, respectively. In a similar way, we extracted CT imaging studies of similar pulmonary syndromes outbreaks caused by other strains of coronavirus family: Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS). For MERS and SARS, 2 out of 21 and 5 out of 153 initially retrieved studies had CT findings, respectively. Herein, we have indicated the most common coronavirus family related and COVID-19 specific features. Presence of GGO, consolidation, bilateral lung involvement and peripheral distribution were the features reported in at least 83% of COVID-19 articles, while air bronchogram, multi-lobe involvement and linear opacity were the three potential COVID-19 specific CT imaging findings. This is necessary to recognize the most promising imaging features for diagnosis and follow-up of patients with COVID-19. Furthermore, we identified co-existed CT imaging features.

scholarly journals Microfluidic nano-scale qPCR enables ultra-sensitive detection of SARS-CoV-2

2020 ◽  
Author(s):  
Xin Xie ◽  
Tamara Gjorgjieva ◽  
Zaynoun Attieh ◽  
Mame Massar Dieng ◽  
Marc Arnoux ◽  
...  
Keyword(s):  
Viral Infections ◽  
Limit Of Detection ◽  
False Negative ◽  
False Negative Rate ◽  
Clinical Samples ◽  
Nasopharyngeal Swab ◽  
Rt Pcr ◽  
Viral Loads ◽  
Nano Scale ◽  
Negative Rate

Background: A major challenge in controlling the COVID-19 pandemic is the high false-negative rate of the commonly used standard RT-PCR methods for SARS-CoV-2 detection in clinical samples. Accurate detection is particularly challenging in samples with low viral loads that are below the limit of detection (LoD) of standard one- or two-step RT-PCR methods. Methods: We implement a three-step approach for SARS-CoV-2 detection and quantification that employs reverse transcription, targeted cDNA preamplification and nano-scale qPCR based on the Fluidigm 192.24 microfluidic chip. We validate the method using both positive controls and nasopharyngeal swab samples. Results: Using SARS-CoV-2 synthetic RNA and plasmid controls, we demonstrate that the addition of a preamplification step enhances the LoD of the Fluidigm method by 1,000-fold, enabling detection below 1 copy/μl. We applied this method to analyze 182 clinical NP swab samples previously diagnosed using a standard RT-qPCR protocol (91 positive, 91 negative) and demonstrate reproducible detection of SARS-CoV-2 over five orders of magnitude (< 1 to 106 viral copies/μl). Crucially, we detect SARS-CoV-2 with relatively low viral load estimates (<1 to 40 viral copies/μl) in 17 samples with negative clinical diagnosis, indicating a potential false negative rate of 18.7% by clinical diagnostic procedures. Conclusion: The three-step nano-scale RT-qPCR method can robustly detect SARS-CoV-2 in samples with relatively low viral loads (< 1 viral copy/μl) and has the potential to reduce the false negative rate of standard RT-PCR-based diagnostic tests for SARS-CoV-2 and other viral infections.

Factors Associated with False Negative and False Positive RT-PCR Test Results for COVID-19 Detection

2021 ◽  
Author(s):  
Shirin Hakimi
Keyword(s):  
False Positive ◽  
False Negative ◽  
Great Accuracy ◽  
Test Time ◽  
Test Results ◽  
Rt Pcr ◽  
Negative Results ◽  
False Negative Results ◽  
Polymerase Chain ◽  
Relevant Factors

The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has spread rapidly and developed the current pandemic and the stressful lifestyle in addition with extreme pressure on people was the consequence of its increasing mortality rate. Since COVID-19 is highly infectious, it is crucial to diagnose the disease timely and initiate preventive measures to control the epidemic. Therefore, the need for accurate detection of this virus has been increased dramatically. Real-Time reverse-transcription Polymerase Chain Reaction (RT-PCR) tests are considered a gold standard to detect SARS-CoV-2 RNA. Besides, the recent pandemic has posed the most serious challenge in PCR applications to date. Although RT-PCR has great accuracy, some factors can reduce the efficiency of this test. Time of testing and type of sample are typical elements that may cause false negative results. Furthermore, false positive cases would be the result of contamination and unoptimized primers. In this paper, the relevant factors creating false positive and false negative results have been investigated in depth to increase the awareness of clinicians.

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