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FACT BRIEF

Did the CDC change the laboratory standard for determining a positive coronavirus test result?

Saturday, May 1, 2021
By Gus Fisher
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NO

Claims that the Centers for Disease Control has changed its coronavirus testing standards are based erroneously on instructions for labs submitting coronavirus specimens for sequencing in further research. CDC standards for determining whether someone has been infected by the virus haven’t changed.

The CDC is asking labs to screen for specimens with relatively high “viral loads” in order to help study so-called “breakthrough” COVID-19 cases among fully vaccinated people. To determine the load, scientists look at a figure called cycle threshold. Generally, a lower figure indicates a higher viral load, facilitating more accurate and complete examination of the virus.

The relationship between a specific threshold and symptoms and progression of COVID-19 disease are not yet well understood. Higher thresholds continue to be used in general testing for the presence of the virus.

This fact brief is responsive to conversations such as this one.
Sources
US Centers for Disease Control COVID-19 vaccine breakthrough case investigation
US Food and Drug Administration CDC Coronavirus test instructions (see p. 36)
US Centers for Disease Control FAQs for labs—Interpreting results of diagnostic tests
Science One number could help reveal how infectious a COVID-19 patient is. Should test results include it?
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Between 2020 and 2022, under close editorial supervision, Gigafact contracted a group of freelance writers and editors to test the concepts for fact briefs and provide inputs to our software development process. We call this effort Gigafact Foundry. Over the course of these two years, Gigafact Foundry writers published over 1500 fact briefs in response to claims they found online. Their important work forms the basis of Gigafact formats and editorial guidelines, and is available to the public on Gigafact.org. Readers should be aware that while there is still a lot of relevant information to be found, not all fact briefs produced by Gigafact Foundry reflect Gigafact's current methods and standards for fact briefs. If you come across any that you feel are out of date and need to be looked at with fresh eyes, don't hesitate to contact us at support@gigafact.org.
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Fact briefs are short, credibly sourced summaries that offer “yes/no” answers in response to claims found online. They rely on publicly available, often primary source data and documents. Fact briefs are created by contributors to Gigafact —a nonprofit project looking to expand participation in fact-checking and protect the democratic process. See all fact briefs here.