IDSA publishes guidelines for SARS-CoV-2 antigen tests
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The Infectious Diseases Society of America published new guidelines for the use of SARS-CoV-2 antigen tests.
“Antigen tests really have become increasingly available over the course of the pandemic and have helped us address a need for more universal and rapid access to diagnostic testing for SARS-CoV-2,” Kimberly E. Hanson, MD, MHS, associate professor of internal medicine and adjunct associate professor of pathology at the University of Utah School of Medicine, said during an IDSA press briefing. “These tests can be used in a variety of settings.”
The guidance was based on a systematic review of the literature by infectious disease clinicians and clinical microbiologists, which found that the clinical performance data on rapid antigen tests that have been granted emergency use authorization by the FDA are “mostly limited to single, one-time testing versus standard nucleic acid amplification testing (NAAT) as the reference standard,” the guidelines panel wrote.
“Rapid antigen tests have high specificity and low to modest sensitivity compared to reference NAAT methods. Antigen test sensitivity is heavily dependent on viral load, with differences observed between symptomatic compared to asymptomatic individuals and the time of testing post onset of symptoms,” the panel wrote.
“Based on these observations, rapid RT-PCR or laboratory-based NAAT remain the diagnostic methods of choice for diagnosing SARS-CoV-2 infection,” the panel continued. “However, when molecular testing is not readily available or is logistically infeasible, antigen testing can help identify some individuals with SARS-CoV-2 infection.”
The guidance, which was based on evidence graded as “very low to moderate,” includes five diagnostic recommendations:
- Symptomatic people with suspected COVID-19 should be tested using NAAT (either a rapid RT-PCR or lab-based NAAT) over antigen tests.
- Asymptomatic people with a risk for exposure to SARS-CoV-2 should be tested via a single standard NAAT (either a rapid RT-PCR or lab-based NAAT) over a single rapid antigen test.
- Asymptomatic people with a risk for SARS-CoV-2 exposure should be given a single standard NAAT (either a rapid RT-PCR or lab-based NAAT) rather than two consecutive rapid antigen tests.
- The panel does not advise for or against single rapid antigen testing as opposed to not testing asymptomatic people with a risk for SARS-CoV-2 exposure.
- The IDSA does not advocate for or against using repeat rapid antigen testing rather than no testing for asymptomatic people with a risk for SARS-CoV-2 exposure.
“When we reviewed the literature and came up with our recommendations and suggestions, it was a time when highly effective vaccines were not widely available and there was not significant coverage of the adult population being vaccinated,” Hanson said. “It is likely that the role of testing will change as we see more vaccination coverage in the population, and the prevalence of infection in communities starts to decline — which we are already starting to see.”
The IDSA said the guidelines were endorsed by the American Society for Microbiology, the Society for Healthcare Epidemiology of America, and the Pediatric Infectious Diseases Society.
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IDSA. IDSA guidelines on the diagnosis of COVID-19: Antigen testing. https://www.idsociety.org/practice-guideline/covid-19-guideline-antigen-testing/. Accessed June 2, 2021.
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