IDSA updates guidelines for COVID-19 molecular testing
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The Infectious Disease Society of America has updated its guidelines for COVID-19 molecular diagnostic tests.
In a press briefing, Angela M. Caliendo, MD, PhD, FIDSA, and Kimberly E. Hanson, MD, MHS, both members of IDSA’s board of directors and chairs of IDSA’s COVID-19 diagnostic guidelines expert panel, discussed revisions to the recommendations regarding sample types, types of molecular testing and screening for asymptomatic individuals.
Regarding sample collection, IDSA now recommends “collecting a nasopharyngeal swab, midturbinate swab, anterior nasal swab, saliva or a combined anterior nasal/oropharyngeal swab rather than an oropharyngeal swab alone for SARS-CoV-2 RNA testing in symptomatic individuals suspected of having COVID-19.” Hanson said labs should ensure they are able to test saliva for the virus because it requires specialized equipment.
The panel also now recommends “using either rapid RT-PCR or standard laboratory-based [nucleic acid amplification tests (NAATs)] over rapid isothermal NAAT in symptomatic individuals suspected of having COVID-19.” Caliendo said it is important that a backup test is provided if an individual tests negative on a rapid isothermal test, but the test administrator strongly suspects the individual has COVID-19 or shows a number of symptoms for the virus.
In two other updates, the panel recommends “RNA testing (vs. no testing) in asymptomatic individuals before hematopoietic stem cell or solid organ transplantation regardless of a known exposure to COVID-19,” and it recommends “against RNA testing in asymptomatic individuals without a known exposure to COVID-19 who are undergoing a time-sensitive aerosol-generating procedure (eg, bronchoscopy) when [personal protective equipment] is available.” Hanson said that screening for the virus in cancer patients or individuals with autoimmune conditions is up to the discretion of the provider.
Caliendo said there is a lack of information on recently authorized at-home COVID-19 tests, and that cost may pose a barrier further down the line. However, she also said the tests can potentially be useful if used correctly.
“It will be very interesting, once those tests get out there in use, to see how easy they are for people to run them at home and how well the whole process works,” Caliendo said. “They’re out there, but I don’t know how available the tests are at this point because both of the tests have recently received their [emergency use authorization]. It’s something to keep your eyes out for.”
Hanson discussed the potential impact of COVID-19 variants on testing.
“What we’ve learned is that there are a lot of different variants out there, some of which have mutations in the spike region from the original classic sequences that were used to design the tests,” she said. “We have not found the U.K. variant in our collection, and we do not think that these polymorphisms or little mutations in the spike regions affect the accuracy of the molecular tests.”
Hanson emphasized the importance of test diversification.
“Being diversified, in terms of not only the sample types that you accept in your lab but diversity in offering different tests for different situations, has helped us in our supply chain,” Hanson said. “We’re not fully reliant on just one supply chain. Opening up additional options for both sample and test types might help labs if they are able to validate multiple different iterations and combinations of different approaches.”
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IDSA. The Infectious Diseases Society of America Guidelines on the diagnosis of COVID-19: Molecular diagnostic testing. https://www.idsociety.org/practice-guideline/covid-19-guideline-diagnostics/. Accessed January 6, 2021.
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