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

Romero-Álvarez, Daniel; Garzon-Chavez, Daniel; Espinosa, Franklin; Ligña, Edison; Terán, Enrique; Mora, Francisco; Espín, Emilia; Albán, Cristina; Galarza, Juan Miguel; Reyes, Jorge E. Fernández

doi:10.2147/rmhp.s282962

Cited by 7 publications

(4 citation statements)

References 26 publications

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“…Unfortunately, the true numbers of false positives will probably be unobtainable if an audit were performed, since these values are not reported with the test results: all currently-available nucleic acid tests for SARS-CoV-2 are FDA-authorized as qualitative tests, and Ct values from qualitative tests should never be used to direct or inform patient management decisions. Therefore, it is not good for laboratories to include Ct values on patient reports ( Romero-Alvarez et al, 2021 ).…”

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confidence: 99%

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“…However, the concentration of the same genes was found higher in the second round of sampling and correlated with higher positive laboratory-confirmed cases. Several previous studies also had the same findings (Romero-Alvarez et al, 2021;Zacharioudakis et al, 2020). Therefore, based on our research findings, Ct values can be used as a tool to determine the trends of viral load which ultimately will help in identifying the number of patients without starting the clinical diagnosis process.…”

Section: Discussionsupporting

confidence: 75%

Wastewater based surveillance system to detect SARS-CoV-2 genetic material for countries with on-site sanitation facilities: an experience from Bangladesh

Jakariya

Ahmed

Islam

et al. 2021

Preprint

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The presence of SARS-CoV-2 genetic materials in wastewater has become a matter of grave for many countries of the world. Wastewater based epidemiology, in this context, emerged as an important tool in developed countries where proper sewage system is available. Due to the recent shift in the spread of the infection from urban to rural areas, it is now equally important to develop a similar mechanism for rural areas as well. Considering the urgency of the issue a study was conducted in 14 districts of Bangladesh and a total of 238 sewage samples were collected in two different periods from December 2020 to January 2021. We are the first to propose a surveillance system for both urban and rural areas where a proper sewage system is absent. Based on RT-PCR analysis of the water samples, in more than 92% of cases, we found the presence of the SARS-COV-2 gene (ORF1ab, N, and Internal Control-IC). The trend of Ct value varies for different study locations. The spread of genetic material for on-site (m = - 0.0386) sanitation system was found more prominent than that of off-site sewage system (m = 0.0105); which indicated the shift of genetic material from urban to rural areas. Wastewater samples were also measured for physicochemical parameters, including pH (6.30 - 12.50) and temperature (22.10 - 32.60)C. The highest viral titer of 1975 copy/mL in sewage sample was observed in a sample collected from the isolation ward of the SARS-COV-2 hospital. Additionally, a correlation was found between bacterial load and SARS-CoV-2 genetic materials. The results indicated the association of increased Ct values with decreasing number of patients and vice versa. The findings reported in this paper contributed to the field of wastewater-based epidemiology dealing with SARS-COV-2 surveillance for developing countries where proper sewage system is absent and highlighting some of the challenges associated with this approach in such settings. Keywords: On-site Sanitation, Off-site Sanitation, SARS-CoV-2, Genetic Materials, Developing Countries, Rural Wastewater-Based Surveillance System.

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“…In addition, one class of scientists has questioned whether RT-PCR be termed a gold standard technique for the detection of SARS-CoV-2 infection [29,30]. Furthermore, recent evidence suggests that correct predictions, combined with efficient analysis of Ct values, can pave the way for improved diagnostic methodology, which can then be used to manage and control virus spread as well as monitor disease progression [31,32]. Given that rapid and accurate detection of SARS-CoV-2 is crucial in controlling the outbreak in the community and in hospitals, this review focuses on the concept of Ct values in COVID-19, and its relationship with disease severity, disease progression and infectivity.…”

Section: Introductionmentioning

confidence: 99%

Viral Dynamics and Real-Time RT-PCR Ct Values Correlation with Disease Severity in COVID-19

et al. 2021

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Real-time RT-PCR is considered the gold standard confirmatory test for coronavirus disease 2019 (COVID-19). However, many scientists disagree, and it is essential to understand that several factors and variables can cause a false-negative test. In this context, cycle threshold (Ct) values are being utilized to diagnose or predict SARS-CoV-2 infection. This practice has a significant clinical utility as Ct values can be correlated with the viral load. In addition, Ct values have a strong correlation with multiple haematological and biochemical markers. However, it is essential to consider that Ct values might be affected by pre-analytic, analytic, and post-analytical variables such as collection technique, specimen type, sampling time, viral kinetics, transport and storage conditions, nucleic acid extraction, viral RNA load, primer designing, real-time PCR efficiency, and Ct value determination method. Therefore, understanding the interpretation of Ct values and other influential factors could play a crucial role in interpreting viral load and disease severity. In several clinical studies consisting of small or large sample sizes, several discrepancies exist regarding a significant positive correlation between the Ct value and disease severity in COVID-19. In this context, a revised review of the literature has been conducted to fill the knowledge gaps regarding the correlations between Ct values and severity/fatality rates of patients with COVID-19. Various databases such as PubMed, Science Direct, Medline, Scopus, and Google Scholar were searched up to April 2021 by using keywords including “RT-PCR or viral load”, “SARS-CoV-2 and RT-PCR”, “Ct value and viral load”, “Ct value or COVID-19”. Research articles were extracted and selected independently by the authors and included in the present review based on their relevance to the study. The current narrative review explores the correlation of Ct values with mortality, disease progression, severity, and infectivity. We also discuss the factors that can affect these values, such as collection technique, type of swab, sampling method, etc.

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

Cited by 7 publications

References 26 publications

RETRACTED: Why are we vaccinating children against COVID-19?

RETRACTED: Why are we vaccinating children against COVID-19?

Wastewater based surveillance system to detect SARS-CoV-2 genetic material for countries with on-site sanitation facilities: an experience from Bangladesh

Viral Dynamics and Real-Time RT-PCR Ct Values Correlation with Disease Severity in COVID-19

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