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Chapter 7 - Development of Assays to Diagnose COVID-19
- Edited by Steven C. Schachter, Harvard Medical School, Wade E. Bolton, VentureWell/Rapid Acceleration of Diagnostics (RADx)
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- Book:
- Accelerating Diagnostics in a Time of Crisis
- Published online:
- 06 January 2024
- Print publication:
- 07 March 2024, pp 125-142
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Summary
This chapter covers the development of diagnostic tests that detect and often amplify severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleic acids (molecular tests) or directly detect protein antigens (antigen tests). In the Rapid Acceleration of Diagnostics (RADx®) Tech program, tests that could be performed by following the instructions for use (Clinical Laboratory Improvement Amendments-waived point-of-care tests) or at home (over the counter) became more ubiquitous and represented a paradigm shift in infectious disease diagnostics away from reference laboratory testing by trained laboratorians. Understanding the clinical use case and unmet need is essential to the development of successfully commercialized tests. Important considerations include sample type and collection, the timing of testing (asymptomatic, contact of a known case, or symptomatic), biosafety, the limit of detection and sensitivity, specificity, the turnaround time, form factor and workflow, internal controls, early verification and validation, and supply chain bottlenecks.
Design and implementation of a digital site-less clinical study of serial rapid antigen testing to identify asymptomatic SARS-CoV-2 infection
- Apurv Soni, Carly Herbert, Caitlin Pretz, Pamela Stamegna, Andreas Filippaios, Qiming Shi, Thejas Suvarna, Emma Harman, Summer Schrader, Chris Nowak, Eric Schramm, Vik Kheterpal, Stephanie Behar, Seanan Tarrant, Julia Ferranto, Nathaniel Hafer, Matthew Robinson, Chad Achenbach, Robert L. Murphy, Yukari C. Manabe, Laura Gibson, Bruce Barton, Laurel O’Connor, Nisha Fahey, Elizabeth Orvek, Peter Lazar, Didem Ayturk, Steven Wong, Adrian Zai, Lisa Cashman, Lokinendi V. Rao, Katherine Luzuriaga, Stephenie Lemon, Allison Blodgett, Elizabeth Trippe, Mary Barcus, Brittany Goldberg, Kristian Roth, Timothy Stenzel, William Heetderks, John Broach, David McManus
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- Journal:
- Journal of Clinical and Translational Science / Volume 7 / Issue 1 / 2023
- Published online by Cambridge University Press:
- 10 May 2023, e120
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- Article
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Background:
Rapid antigen detection tests (Ag-RDT) for SARS-CoV-2 with emergency use authorization generally include a condition of authorization to evaluate the test’s performance in asymptomatic individuals when used serially. We aim to describe a novel study design that was used to generate regulatory-quality data to evaluate the serial use of Ag-RDT in detecting SARS-CoV-2 virus among asymptomatic individuals.
Methods:This prospective cohort study used a siteless, digital approach to assess longitudinal performance of Ag-RDT. Individuals over 2 years old from across the USA with no reported COVID-19 symptoms in the 14 days prior to study enrollment were eligible to enroll in this study. Participants throughout the mainland USA were enrolled through a digital platform between October 18, 2021 and February 15, 2022. Participants were asked to test using Ag-RDT and molecular comparators every 48 hours for 15 days. Enrollment demographics, geographic distribution, and SARS-CoV-2 infection rates are reported.
Key Results:A total of 7361 participants enrolled in the study, and 492 participants tested positive for SARS-CoV-2, including 154 who were asymptomatic and tested negative to start the study. This exceeded the initial enrollment goals of 60 positive participants. We enrolled participants from 44 US states, and geographic distribution of participants shifted in accordance with the changing COVID-19 prevalence nationwide.
Conclusions:The digital site-less approach employed in the “Test Us At Home” study enabled rapid, efficient, and rigorous evaluation of rapid diagnostics for COVID-19 and can be adapted across research disciplines to optimize study enrollment and accessibility.
110 - Tuberculosis
- from PART XIV - INFECTIONS
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- By Yukari C. Manabe, Johns Hopkins University School of Medicine, Baltimore, MD, USA, Richard E. Chaisson, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Edited by Arthur K. Asbury, University of Pennsylvania School of Medicine, Guy M. McKhann, The Johns Hopkins University School of Medicine, W. Ian McDonald, University College London, Peter J. Goadsby, University College London, Justin C. McArthur, The Johns Hopkins University School of Medicine
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- Book:
- Diseases of the Nervous System
- Published online:
- 05 August 2016
- Print publication:
- 11 November 2002, pp 1777-1790
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Summary
Despite the availability of curative therapy and a widely used vaccine, tuberculosis is one of the greatest threats to human health and continues to cause enormous suffering, disability and death. Infections with Mycobacterium tuberculosis cause a wide array of clinical manifestations, ranging from asymptomatic latent infection to disseminated and fulminant disease. Tuberculosis is generally regarded as a respiratory infection, but early in M. tuberculosis infection the organism is hematogenously disseminated and takes up residence in a number of organs, including the central nervous system. Tuberculosis affects the central nervous system in three principal ways: tuberculous meningitis, tuberculomas of the brain and spinal cord, and vertebral tuberculosis, or Pott's disease, an infection of vertebrae and paraspinous areas that can lead to destabilization of the spinal cord with potentially devastating neurological consequences. The purpose of this chapter is to describe the neurologic manifestations of tuberculosis and discuss its diagnosis and management.
Epidemiology
Tuberculosis remains a global problem with 8 million new cases per year and approximately 2 million deaths. Twentytwo countries account for 80% of all tuberculosis cases, and the case rate in developing countries is approximately sevenfold higher than in industrialized nations. Globally, increasing rates of HIV-related tuberculosis have been noted in areas where tuberculosis infection is endemic and HIV is epidemic. Tuberculosis is the most common opportunistic infection in people with HIV, and more HIVinfected individuals die from tuberculosis than any other cause. In many countries where HIV is not prevalent, tuberculosis remains a common cause of disability and death, primarily affecting young adults.
M. tuberculosis epidemiology can be divided into two components based on the natural history of the organism in humans: latent infection with M. tuberculosis, which is acquired from infectious cases of tuberculosis, and tuberculosis disease, which results from either primary or remote progression of a latent infection to clinical illness. Risk factors for acquiring tuberculosis infection include close contact with an infectious case, often in the same household or workplace, or exposure to air shared by infectious tuberculosis patients, such as in health care facilities or in public places in high prevalence communities. Socioeconomic factors associated with tuberculosis infection generally reflect an increased likelihood of exposure to others with active disease. Risk factors for developing active tuberculosis disease include recent infection, large inoculum, and impaired cellular immunity, such as with HIV infection or pharmacological immunosuppression.