How accurate is the SARS-CoV-2 antigen test?

How Accurate is the SARS-CoV-2 Antigen Test?

Antigen tests for SARS-CoV-2, the virus responsible for COVID-19, have become a popular tool in managing the pandemic due to their affordability and ability to yield results rapidly. This article evaluates the accuracy of these tests and discusses significant factors influencing their reliability.

Table of Contents

  1. Introduction
  2. Overview of Antigen Test Accuracy
  3. Sensitivity and Specificity
  4. Factors Influencing Test Accuracy
  5. Notable Company Solutions
  6. References

Introduction

The SARS-CoV-2 antigen tests are designed to detect specific proteins from the virus, offering potential for quick diagnosis. These tests are especially useful in settings where rapid results are necessary, such as airports, schools, and workplaces.

Overview of Antigen Test Accuracy

SARS-CoV-2 antigen tests generally display varied levels of accuracy, specifically in sensitivity and specificity measurements. These terms are key metrics used to assess diagnostic tests.

Sensitivity and Specificity

The sensitivity of a test refers to its ability to correctly identify those with the disease (true positive rate), while specificity refers to its ability to correctly identify those without the disease (true negative rate).

Many SARS-CoV-2 antigen tests have reported sensitivity levels ranging from 50% to 80%, significantly lower than the reverse transcription polymerase chain reaction (RT-PCR) tests which generally exceed 90% sensitivity. Specificity for antigen tests is often higher, frequently exceeding 95%, though variations exist between different tests and manufacturers.

Factors Influencing Test Accuracy

The accuracy of SARS-CoV-2 antigen tests can be influenced by several factors:

  • Timing of the Test: Testing accuracy is higher when individuals are symptomatic and during peak viral load periods.
  • Sample Quality: Proper sample collection and handling are crucial for reliable results.
  • Test Implementation: Variability in compliance with manufacturer guidelines can lead to inconsistent outcomes.

Notable Company Solutions

Various companies have developed antigen testing solutions with varying performance capabilities:

  • Abbott Laboratories: The BinaxNOW test offers results in 15 minutes and demonstrates 84.6% sensitivity and 98.5% specificity.
  • Quidel Corporation: The Sofia SARS Antigen FIA provides results in approximately 15 minutes, with a reported 80% sensitivity and 99% specificity.
  • BD (Becton, Dickinson and Company): The Veritor System for Rapid Detection ensures results in 15 minutes with a 76% sensitivity and 98% specificity.

References

  1. World Health Organization. (2020). Antigen-detection in the diagnosis of SARS-CoV-2 infection using rapid immunoassays.
  2. Food and Drug Administration. (2021). In Vitro Diagnostics EUAs.
  3. Paltiel, A. D., Zheng, A., & Walensky, R. P. (2020). Assessment of SARS-CoV-2 Screening Strategies to Permit the Safe Reopening of College Campuses in the United States. JAMA Network Open.
  4. Abbott Laboratories. BinaxNOW COVID-19 Ag Card Fact Sheet for Healthcare Providers.
  5. Quidel Corporation. Sofia SARS Antigen FIA Fact Sheet for Healthcare Providers.
  6. BD (Becton, Dickinson and Company). Veritor System for Rapid Detection of SARS Antigen Factsheet.
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