scholarly journals The 501Y.V2 SARS-CoV-2 variant has an intermediate viral load between the 501Y.V1 and the historical variants in nasopharyngeal samples from newly diagnosed COVID-19 patients

2021 ◽  
Author(s):  
Elisa Teyssou ◽  
Cathia Soulie ◽  
Benoit Visseaux ◽  
Sidonie Lambert-Niclot ◽  
Valentine Ferre ◽  
...  
Keyword(s):  
Viral Load ◽  
Newly Diagnosed ◽  
Threshold Values ◽  
Rt Pcr ◽  
Cycle Threshold ◽  
The World

The 501Y.V2 and the 501Y.V1 SARS-CoV-2 variants emerged and spread rapidly into the world. We analysed the RT-PCR cycle threshold values of 643 nasopharyngeal samples of COVID-19 patients at diagnosis and found that the 501Y.V2 variant presented an intermediate viral load between the 501Y.V1 and the historical variants.

scholarly journals Duration of infectiousness and correlation with RT-PCR cycle threshold values in cases of COVID-19, England, January to May 2020

2020 ◽  
Vol 25 (32) ◽  
Author(s):  
Anika Singanayagam ◽  
Monika Patel ◽  
Andre Charlett ◽  
Jamie Lopez Bernal ◽  
Vanessa Saliba ◽  
...  
Keyword(s):  
Viral Load ◽  
Severe Acute Respiratory Syndrome ◽  
Respiratory Tract ◽  
Symptom Onset ◽  
Infectious Virus ◽  
Upper Respiratory Tract ◽  
Threshold Values ◽  
Rt Pcr ◽  
Cycle Threshold ◽  
Upper Respiratory

Severe acute respiratory syndrome coronavirus 2 viral load in the upper respiratory tract peaks around symptom onset and infectious virus persists for 10 days in mild-to-moderate coronavirus disease (n = 324 samples analysed). RT-PCR cycle threshold (Ct) values correlate strongly with cultivable virus. Probability of culturing virus declines to 8% in samples with Ct > 35 and to 6% 10 days after onset; it is similar in asymptomatic and symptomatic persons. Asymptomatic persons represent a source of transmissible virus.

scholarly journals Preanalytical Issues and Cycle Threshold Values in SARS-CoV-2 Real-Time RT-PCR Testing: Should Test Results Include These?

ACS Omega ◽  
2021 ◽  
Author(s):  
Ilka Engelmann ◽  
Enagnon Kazali Alidjinou ◽  
Judith Ogiez ◽  
Quentin Pagneux ◽  
Sana Miloudi ◽  
...  
Keyword(s):  
Real Time ◽  
Test Results ◽  
Threshold Values ◽  
Rt Pcr ◽  
Cycle Threshold

scholarly journals Cycle Threshold Values in the Context of Multiple RT-PCR Testing for SARS-CoV-2

2021 ◽  
Vol Volume 14 ◽  
pp. 1311-1317
Author(s):  
Daniel Romero-Alvarez ◽  
Daniel Garzon-Chavez ◽  
Franklin Espinosa ◽  
Edison Ligña ◽  
Enrique Teran ◽  
...  
Keyword(s):  
Threshold Values ◽  
Rt Pcr ◽  
Cycle Threshold

scholarly journals Distribution of SARS-CoV-2 PCR Cycle Threshold Values Provide Practical Insight Into Overall and Target-Specific Sensitivity Among Symptomatic Patients

2020 ◽  
Vol 154 (4) ◽  
pp. 479-485 ◽  
Author(s):  
Blake W Buchan ◽  
Jessica S Hoff ◽  
Cameron G Gmehlin ◽  
Adriana Perez ◽  
Matthew L Faron ◽  
...  
Keyword(s):  
Viral Load ◽  
Limit Of Detection ◽  
False Negative ◽  
Age Group ◽  
Rt Pcr ◽  
Patient Age ◽  
Cycle Threshold ◽  
Negative Results ◽  
Patient Âgé ◽  
False Negative Results

Abstract Objectives We examined the distribution of reverse transcription polymerase chain reaction (RT-PCR) cycle threshold (CT) values obtained from symptomatic patients being evaluated for coronavirus disease 2019 (COVID-19) to determine the proportion of specimens containing a viral load near the assay limit of detection (LoD) to gain practical insight to the risk of false-negative results. We also examined the relationship between CT value and patient age to determine any age-dependent difference in viral load or test sensitivity. Methods We collected CT values obtained from the cobas severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) assay corresponding to 1,213 combined nasopharyngeal-oropharyngeal specimens obtained from symptomatic individuals that were reported as positive or presumptive positive for SARS-CoV-2. CT values were stratified by SARS-CoV target and patient age group. Results In total, 93.3% to 98.4% of specimens demonstrated CT values greater than 3× the assay LoD, at which point false-negative results would not be expected. The mean of CT values between age groups was statistically equivalent with the exception of patients in age group 80 to 89 years, which demonstrated slightly lower CTs. Conclusions Based on the distribution of observed CT values, including the small proportion of specimens with values near the assay LoD, there is a low risk of false-negative RT-PCR results in combined nasopharyngeal-oropharyngeal specimens obtained from symptomatic individuals.

Factors associated with real-time RT-PCR cycle threshold values among medically attended influenza episodes

2015 ◽  
Vol 88 (4) ◽  
pp. 719-723 ◽  
Author(s):  
Sarah Spencer ◽  
Jessie Chung ◽  
Mark Thompson ◽  
Pedro A. Piedra ◽  
Alan Jewell ◽  
...  
Keyword(s):  
Real Time ◽  
Threshold Values ◽  
Rt Pcr ◽  
Factors Associated ◽  
Cycle Threshold

scholarly journals Incorporating temporal distribution of population-level viral load enables real-time estimation of COVID-19 transmissibility

2021 ◽  
Author(s):  
Yun Lin ◽  
Bingyi Yang ◽  
Sarah Cobey ◽  
Eric Lau ◽  
Dillon Adam ◽  
...  
Keyword(s):  
Viral Load ◽  
Real Time ◽  
Temporal Distribution ◽  
Time Estimation ◽  
Population Level ◽  
Reproductive Number ◽  
Threshold Values ◽  
Illness Onset ◽  
Cycle Threshold ◽  
Viral Loads

Abstract Many locations around the world have used real-time estimates of the time-varying effective reproductive number (\({R}_{t}\)) of COVID-19 to provide evidence of transmission intensity to inform control strategies. Estimates of \({R}_{t}\) are typically based on statistical models applied to case counts and typically suffer lags of more than a week because of the incubation period and reporting delays. Noting that viral loads tend to decline over time since illness onset, analysis of the distribution of viral loads among confirmed cases can provide insights into epidemic trajectory. Here, we analyzed viral load data on confirmed cases during two local epidemics in Hong Kong, identifying a strong correlation between temporal changes in the distribution of viral loads (measured by cycle threshold values) and estimates of \({R}_{t}\) based on case counts. We demonstrate that cycle threshold values could be used to improve real-time \({R}_{t}\) estimation, enabling more timely tracking of epidemic dynamics.

scholarly journals Infants have lower RT-PCR cycle threshold for SARS-CoV-2 in comparison with older children and adults

2021 ◽  
Author(s):  
Marcia Polese-Bonatto ◽  
Ivaine Tais Sauthier Sartor ◽  
Fernanda Hammes-Varela ◽  
Gabriela Luchiari Tumioto Gianinni ◽  
Thais Raupp Azevedo ◽  
...  
Keyword(s):  
Viral Load ◽  
Significant Role ◽  
Signs And Symptoms ◽  
Viral Dynamics ◽  
Older Children ◽  
Rt Pcr ◽  
Pcr Assay ◽  
Cycle Threshold ◽  
The Mean

Background: The viral dynamics and the role of children in the spread of SARS-CoV-2 are not completely understood. Our aim was to evaluate how RT-PCR Ct values among children with confirmed SARS-CoV-2 compared with that of adult subjects. Methods: Patients (aged from 2 months to ≤18 years, and adults) with signs and symptoms of acute SARS-CoV-2 infection for less than 7 days, were prospectively enrolled in the study from May to November 2020. All participants performed RT-PCR assay for SARS-CoV-2 detection; Ct values of ORF1ab, N, and S gene-targets, and the average of all the three probes were used as surrogates of viral load. Results: Of the total of 376 participants with confirmed SARS-CoV-2 infection there were 21 infants, 62 children and 293 adults. The RT-PCR Ct values of children under 18 were not significantly different from that of adults, as observed by the analyzed probes (namely ORF1ab, N, and S), and by the mean of all 3 gene-targets. However, infants had significantly lower Ct values compared to children and adults (P = 0.044). Discussion: Ct values for children were not significantly different than that of adults with positive SARS-CoV-2. Interestingly, infants had even lower Ct values when compared to older children and adults. Although viral load is not the only determinant of transmission, infants may play a significant role in the spread of SARS-CoV-2 in the community, especially if or when this population returns to regular daycare activities.

scholarly journals Association of cycle threshold values of CBNAAT with severity and outcome in COVID-19

2021 ◽  
Author(s):  
Kranti Garg ◽  
Karan Sharma ◽  
Aditi Gupta ◽  
Vishal Chopra
Keyword(s):  
Viral Load ◽  
Virus Disease ◽  
Nucleic Acid Amplification ◽  
Clinical Parameters ◽  
Surrogate Markers ◽  
Threshold Values ◽  
Cycle Threshold ◽  
E Gene ◽  
Disease Outcomes

Determination of viral load through cycle threshold (Ct) values may act as a predictor of severity and outcomes in patients with corona virus disease 2019 (COVID-19). However, variable literature is available regarding this relationship. Our study attempted to explore this association and the effect of various socio-demographic and clinical parameters on severity and outcome of COVID-19.  Retrospective analysis of records of 731 patients whose nasopharyngeal/ oropharyngeal swabs were subjected to cartridge based nucleic acid amplification (CBNAAT) on Cepheid Xpert Xpress SARS-Cov-2 was done. Cycle threshold (Ct) values of N2 and E genes were studied in relation to severity and outcome of COVID-19. The viral load as determined by Ct values was classified as high (<25), medium (25.1-32) and low (>32). Association of socio-demographic and clinical parameters with respect to severity and outcome was also studied. Severity and mortality were significantly more in elder individuals, those belonging to the rural background, those with symptoms >7 days in duration before presentation and those with increasing number of co-morbidities (Severity: p<0.001, mortality: p <0.001, 0.005, 0.006 and <0.001 respectively). The Ct values of gene N2 and E inversely correlated with severity and mortality from the disease (N2 gene: p=0.001 for both severity and mortality, E gene: severity: p<0.001, mortality: p=0.016 respectively). The severity of the illness and chances of mortality were significantly lesser when the CT value of N2 gene was >32, in comparison when it was upto 25, and when between 25.1 and 32 (severity: p=0.032 and 0.003 respectively, mortality: p=0.018 and <0.001 respectively). Almost similar trends were seen with respect to E gene (severity: p<0.001 and 0.067 respectively, mortality p=0.175 and 0.005 respectively). Viral load as determined by Ct values of N2 and E genes can act as surrogate markers for prediction of severity and disease outcomes in COVID-19.

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