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ReviewPublication 2022Diagnostics for COVID-19: Moving from Pandemic Response to Control
Diagnostics are essential in managing the COVID-19 pandemic, with three primary methods for detecting SARS-CoV-2 …
Diagnostics are essential in managing the COVID-19 pandemic, with three primary methods for detecting SARS-CoV-2 infections. Each test type remains vital as we shift from responding to controlling the pandemic. Molecular tests, like PCR, are highly precise in identifying viral RNA and are endorsed by the WHO for confirming cases and guiding public health actions. Antigen rapid tests spot viral proteins and, while less accurate than molecular tests, are quicker, more affordable, simpler, and can…
Test Performance | Infectious Diseases | Health Systems | Clinical Care | Health/Medicine | Science/Technology -
ReviewPublication 2022Rapid, Point-of-Care Antigen Tests for Diagnosis of SARS-CoV-2 Infection
This study reviewed the diagnostic accuracy of rapid, point-of-care antigen tests for detecting SARS-CoV-2 infection, …
This study reviewed the diagnostic accuracy of rapid, point-of-care antigen tests for detecting SARS-CoV-2 infection, differentiating results between symptomatic and asymptomatic individuals. Using data from 155 study cohorts, the study found that the sensitivity of antigen tests was generally higher for symptomatic individuals, especially during the first week after symptom onset, due to higher viral loads. For example, average sensitivity was higher in symptomatic (73.0%) compared to asymptomatic participants (54.7). Average sensitivity was higher in…
Test Performance | Infectious Diseases | Clinical Care | Health/Medicine | Science/Technology | North America -
ArticlePublication 2020Interpreting COVID-19 Test Results: A Bayesian Approach
This article considers the following question with respect to interpreting the results of polymerase chain reaction …
This article considers the following question with respect to interpreting the results of polymerase chain reaction (PCR) assays from nasal and pharyngeal swabs for COVID-19 to inform clinical decision making: "While a positive result in an acutely ill patient is straightforward, how should physicians interpret negative tests in patients with suspected COVID-19 infection?" Using an assumption of near-perfect specificity of PCR assays for COVID-19, the authors acknowledge the uncertainty of test sensitivity. They consider two clinical scenarios…
Probability/Bayes | Test Performance | Infectious Diseases | Health/Medicine | Science/Technology | Global -
ArticlePublication 2020Interpreting a COVID-19 Test Result
Viral RNA tests for COVID-19, using reverse transcriptase polymerase chain reaction (RT-PCR), rely on samples …
Viral RNA tests for COVID-19, using reverse transcriptase polymerase chain reaction (RT-PCR), rely on samples obtained from the respiratory tract by nasopharyngeal swab. Testing for COVID-19 theoretically could "identify infected individuals who can then be isolated to reduce spread, allow contact tracing for exposed individuals, and provide knowledge of regional and national rates of infection to inform public health interventions." However, how to interpret test results with respect to individual patient results is not straightforward.…
Probability/Bayes | Test Performance | Value of Information | Infectious Diseases | Health/Medicine | Science/Technology | Global -
EditorialPublication 2020Interpreting Diagnostic Tests for SARS-CoV-2
This viewpoint describes how to interpret two types of diagnostic tests commonly used for SARS-CoV-2 …
This viewpoint describes how to interpret two types of diagnostic tests commonly used for SARS-CoV-2 infections – reverse transcriptase-polymerase chain reaction (RT-PCR) and IgM and IgG enzyme-linked immunosorbent assay (ELISA) – and how the results may vary over time. False-negative results mainly occurred due to inappropriate timing of sample collection in relation to illness onset and deficiency in sampling technique, especially of nasopharyngeal swabs. Specificity of most of the RT-PCR tests is 100% because the…
Evidence Synthesis | Test Performance | Infectious Diseases | Health/Medicine | Science/Technology | Global -
ArticlePublication 2016Spectrum Effect in Tests for Risk Prediction, Screening, and Diagnosis
This article discusses the impact of the spectrum effect on measures of test performance, and …
This article discusses the impact of the spectrum effect on measures of test performance, and its implications for the development, evaluation, application, and implementation of such tests. The authors describe this effect as the variation between settings in performance of tests used to predict, screen for, and diagnose disease among different population subgroups. They emphasize that a test developed in a population with a higher prevalence of disease (or at higher risk) will typically have…
Evidence Synthesis | Test Performance | Clinical Care | Health/Medicine | Science/Technology -
ArticlePublication 2020Clinical Decision Making: Using a Diagnostic Test
This article is part of a 6-part series on clinical decision making. The authors use …
This article is part of a 6-part series on clinical decision making. The authors use two clinical examples to review the principles of interpreting diagnostic test results. They outline an approach that can be used to determine how to select and apply tests and their results to the practice of internal medicine. Topics covered in the two case studies include sensitivity and specificity, positive predictive and negative predictive value of tests, and how to estimate…
Probability/Bayes | Test Performance | Clinical Care | Health/Medicine -
EditorialPublication 2020Diagnostic Testing for the Novel Coronavirus
This perspective provides insights about the controversies over diagnostic testing that have dominated U.S. headlines …
This perspective provides insights about the controversies over diagnostic testing that have dominated U.S. headlines regarding severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the novel coronavirus responsible for coronavirus disease-2019 (COVID-19). The authors review early testing challenges, beginning with the initial technical problems with the first test developed by the Centers for Disease Control and Prevention (CDC), which left the U.S. with inadequate diagnostic capacity early in the epidemic. They discuss the "diagnostic testing gap"…
Test Performance | Infectious Diseases | Policy/Regulation | Clinical Care | Government/Law | Health/Medicine | Science/Technology | North America -
ArticlePublication 2020Bayes' Theorem, COVID-19, and Screening Tests
This article reviews the implications of increased testing for COVID-19 using reverse transcriptase polymerase chain …
This article reviews the implications of increased testing for COVID-19 using reverse transcriptase polymerase chain reaction (rRT-PCR) through the application of Bayes’ Theorem for three hypothetical, stylized case scenarios. The scenarios involve three patients with a low, moderate, and high pre-test probability of COVID-19 infection. The category of low probability would include "asymptomatic individuals in a presumed low prevalence environment" and might vary from 10 to 20%. The category of moderate probability would include "individuals…
Probability/Bayes | Test Performance | Infectious Diseases | Clinical Care | Health/Medicine -
EditorialPublication 2020False Negative Tests for SARS-CoV-2 Infection – Challenges and Implications
This article discusses the implications of uncertain test performance within the contextualized rationale for widespread …
This article discusses the implications of uncertain test performance within the contextualized rationale for widespread SARS-CoV-2 testing as essential to safely reopen the U.S. They argue that while much attention has been given to test availability, test accuracy may be the larger long-term problem. Authors provide a solid review of the relationship and influence of the prior probability, test sensitivity, and test specificity on the post-test probability of disease. They connect the quantitative information with…
Test Performance | Infectious Diseases | Clinical Care | Health/Medicine -
EditorialPublication 2020Waiting for Certainty on COVID-19 Antibody Tests — At What Cost?
This perspective anticipates the availability of serologic antibody testing and considers its potential usefulness in mitigation …
This perspective anticipates the availability of serologic antibody testing and considers its potential usefulness in mitigation policy to reduce COVID-19 transmission. For example: Could we screen for serologic antibodies as a proxy for possible immunity and identify people who could return to the workplace with less severe mitigation measures? The authors acknowledge the uncertainties raised by many policy actors, including the WHO, such as, "Do antibodies confer immunity and, if so, for how long? How accurate is…
Probability/Bayes | Test Performance | Technology Assessment | Infectious Diseases | Health Systems | Policy/Regulation | Government/Law | Health/Medicine | Global | North America -
ArticlePublication 2020Testing for SARS-CoV-2 Antibodies
Antibody testing can determine previous exposure to SARS-CoV-2 virus. Recently, the UK government has made …
Antibody testing can determine previous exposure to SARS-CoV-2 virus. Recently, the UK government has made antibody testing available to anyone wanting it, even if there is no clinical indication. The purpose of this article is to provide guidance for when to consider antibody testing in individuals with and without symptoms suggestive of current or past SARS-CoV-2 infection. Key points made by the authors include: (1) antibody testing is likely to be most useful 2 weeks…
Probability/Bayes | Test Performance | Technology Assessment | Infectious Diseases | Clinical Care | Health/Medicine -
ArticlePublication 2020Explosion of New Coronavirus Tests That Could Help to End the Pandemic
The standard test to detect SARS-CoV-2, the reverse-transcription polymerase chain reaction, or RT-PCR, requires trained …
The standard test to detect SARS-CoV-2, the reverse-transcription polymerase chain reaction, or RT-PCR, requires trained personnel, specific chemical supplies and expensive instruments that take hours to provide results and are often available only in labs that provide routine, centralized services. This limits the number of tests that can be done, especially in developing countries. Research groups around the world are now devising tests that go beyond PCR. Dozens of diagnostic methods are in development, all of…
Test Performance | Infectious Diseases | Clinical Care | Business/Industry | Health/Medicine -
ReviewPublication 2020Antibody Tests for Identification of Current and Past Infection with SARS-CoV-2
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus and resulting COVID-19 pandemic present important …
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus and resulting COVID-19 pandemic present important diagnostic challenges. Several diagnostic strategies are available to identify current infection, rule out infection, identify people in need of care escalation, or to test for past infection and immune response. Serology tests to detect the presence of antibodies to SARS-CoV-2 aim to identify previous SARS-CoV-2 infection and may help to confirm the presence of current infection. The objective of this…
Test Performance | Infectious Diseases | Clinical Care | Health/Medicine | Science/Technology -
ReviewPublication 2020Performance Characteristics of 5 Immunoassays for SARS-CoV-2
SARS-CoV-2 antibodies typically start to appear at least 5–7 days post infection and are therefore …
SARS-CoV-2 antibodies typically start to appear at least 5–7 days post infection and are therefore an unreliable marker for early acute infection. The degree and duration of immunity that antibodies confer are unclear. A prominent use for serological testing has therefore been at a population level, for informing the extent of population exposure. Immunoassays used for SARS-CoV-2 testing detect either specific types of antibody (e.g., IgM or IgG) or total antibody. To date, few thorough, direct…
Test Performance | Infectious Diseases | Clinical Care | Health/Medicine | Science/Technology -
ReviewPublication 2020Rapid, Point-of-Care Tests for Diagnosis of SARS-CoV-2 Infection
Several diagnostic strategies are available to identify or rule out current infection with SARS-CoV-2, identify …
Several diagnostic strategies are available to identify or rule out current infection with SARS-CoV-2, identify people in need of care escalation, or to test for past infection and immune response. Point-of-care antigen and molecular tests to detect current SARS-CoV-2 infection have the potential to allow earlier detection and isolation of confirmed cases compared to laboratory-based diagnostic methods, with the aim of reducing household and community transmission. This study sought to assess the diagnostic accuracy of point-of-care antigen and…
Test Performance | Infectious Diseases | Clinical Care | Health/Medicine | Science/Technology -
ArticlePublication 2023Performance of Rapid Antigen Tests to Detect Symptomatic and Asymptomatic SARS-CoV-2 Infection
The objective of this study was to evaluate the performance of rapid antigen tests (Ag-RDTs) …
The objective of this study was to evaluate the performance of rapid antigen tests (Ag-RDTs) for detection of SARS-CoV-2 among symptomatic and asymptomatic participants. The general findings were that the performance of Ag-RDTs was optimized when asymptomatic participants tested 3 times at 48-hour intervals and when symptomatic participants tested 2 times separated by 48 hours. Participants completed Ag-RDTs and reverse transcriptase polymerase chain reaction (RT-PCR) testing for SARS-CoV-2 every 48 hours for 15 days. They…
Test Performance | Infectious Diseases | Clinical Care | Health/Medicine | Science/Technology | North America -
ArticlePublication 2020Variation in False-Negative Rate of Reverse Transcriptase Polymerase Chain Reaction-Based SARS-CoV-2 Tests by Time Since Exposure
This study aimed to determine the false-negative rate of RT-PCR tests for SARS-CoV-2 infection based …
This study aimed to determine the false-negative rate of RT-PCR tests for SARS-CoV-2 infection based on the timeline of exposure and symptom onset. Drawing from data in seven studies involving 1,330 upper respiratory tract samples, a Bayesian model was used to estimate these rates. Findings showed that in the initial four days prior to typical symptom onset, the false-negative rate decreased from 100% on day 1 to 67% on day 4. By the day of…
Test Performance | Infectious Diseases | Clinical Care | Health/Medicine | Science/Technology | North America -
ReviewPublication 2021Considerations for Diagnostic COVID-19 Tests
During the initial stages of the COVID-19 pandemic, there was a rush by numerous diagnostic …
During the initial stages of the COVID-19 pandemic, there was a rush by numerous diagnostic test manufacturers to create, validate, and implement testing methods. This review discusses the pivotal role of diagnostic tests during the pandemic's first global wave, highlighting the challenges in technology and implementation experienced early on. The study also offers insights for enhancing the use of diagnostics, especially syndromic ones, should there be future spikes or regional outbreaks of COVID-19. The overarching…
Test Performance | Infectious Diseases | Clinical Care | Health/Medicine | Science/Technology | North America -
ArticlePublication 2022Estimated Transmission Outcomes and Costs of SARS-CoV-2 Diagnostic Testing, Screening, and Surveillance Strategies Among a Simulated Population of Primary School Students
In the wake of the COVID-19 pandemic's significant educational disruptions, the U.S. government allocated $10 …
In the wake of the COVID-19 pandemic's significant educational disruptions, the U.S. government allocated $10 billion in March 2021 for testing in schools. The study aimed to analyze the costs and benefits of different COVID-19 testing strategies, particularly focusing on full-time, in-person elementary and middle school education. Utilizing an updated agent-based network model, the study simulated transmission scenarios in schools, considering various testing strategies ranging from diagnostic testing (test-to-stay) to reduce symptom-based isolations, routine screening…
Test Performance | Mathematical Models | Cost-Effectiveness Analysis | Infectious Diseases | Clinical Care | Health/Medicine | Science/Technology | North America -
ArticlePublication 2021Racial and Ethnic Inequities in the Early Distribution of U.S. COVID-19 Testing Sites and Mortality
In 2020, U.S. COVID-19 testing sites were pivotal not just for diagnosis but also to …
In 2020, U.S. COVID-19 testing sites were pivotal not just for diagnosis but also to provide data that would contribute to understanding transmission. This research explored how these sites were distributed in relation to racial and ethnic demographics and its connection to observed disparities in COVID-19 outcomes. Data from mid-April to late May 2020 revealed that testing sites were not equally distributed among racial groups. Specifically, there was an overrepresentation of testing sites in areas…
Health Outcomes | Test Performance | Infectious Diseases | Social Determinants | Policy/Regulation | Culture/Society | Health/Medicine | Science/Technology | North America -
ArticlePublication 2022Modeling the Effectiveness of Healthcare Personnel Reactive Testing and Screening for the SARS-Cov-2 Omicron Variant within Nursing Homes
The Omicron variant of SARS-CoV-2 has been hypothesized to exhibit faster clearance (time from peak …
The Omicron variant of SARS-CoV-2 has been hypothesized to exhibit faster clearance (time from peak viral concentration to clearance of acute infection), may be less detectable by antigen tests (decreased sensitivity), and may be more likely to evade immunity conferred by past infection or vaccination) compared to prior variants. This calls for a reassessment of strategies to prevent its spread, especially in vulnerable settings like nursing homes. Using a model that tracks viral shedding patterns,…
Test Performance | Mathematical Models | Infectious Diseases | Health/Medicine | North America -
ReviewPublication 2022Significance of Advanced COVID-19 Diagnostic Testing in Pandemic Control Measures
Over the past two years of the COVID-19 pandemic, the scientific community has mounted significant …
Over the past two years of the COVID-19 pandemic, the scientific community has mounted significant efforts to combat the highly transmissible SARS-CoV-2 virus. Despite substantial progress in vaccines and treatments, leading to lower hospitalization and death rates, the virus has continued to evolve, primarily through mutations. From the onset, diagnostic tests have been crucial in identifying and controlling the virus spread. The scientific world has pioneered various diagnostic techniques, including nucleic acid, antigen, and antibody-based…
Test Performance | Infectious Diseases | Health Systems | Clinical Care | Health/Medicine | Science/Technology | North America -
ArticlePublication 2022Comparison of Home Antigen Testing With RT-PCR and Viral Culture During the Course of SARS-CoV-2 Infection
As the availability of at-home self-collected antigen tests for SARS-CoV-2 increases, understanding their efficacy is …
As the availability of at-home self-collected antigen tests for SARS-CoV-2 increases, understanding their efficacy is crucial. A study in San Diego and Denver between January and May 2021 assessed the reliability of these tests against standard RT-PCR tests and viral cultures. Of the 225 participants with confirmed infections, the antigen test sensitivity was found to be 50% during the infectious period, 64% against the same-day RT-PCR, and 84% against the same-day cultures. Sensitivity was highest…
Test Performance | Infectious Diseases | Clinical Care | Culture/Society | Health/Medicine | Science/Technology
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