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Posts circulating on Facebook and Instagram claim that the Centers for Disease Control and Prevention will stop using its COVID-19 test because it cannot tell the difference between the COVID virus and influenza viruses.
“The CDC has just announced that it will revoke the authorization for the emergency use of RT-PCR tests introduced for the first time in 2/20,” reads a July 25 article, which goes on to quote The agency’s lab guideline: “The CDC encourages labs to consider adopting a multiplexed method that can facilitate detection and differentiation of SARS CoV-2 and influenza viruses.” He continues: ” Translation: They added influenza cases to COVID cases when using this test. “
Mike Huckabee, a former Fox News host who was also a Republican presidential candidate and governor of Arkansas, also claimed on Facebook that the CDC test cannot tell the difference between coronaviruses and flu viruses.
A July 24 Instagram post went further: “The FDA today announced that the CDC PCR test has failed its full review. Emergency use authorization has been REVOCATED.
The posts were reported as part of Facebook’s efforts to tackle fake news and disinformation on its news feed. (Learn more about PolitiFact’s partnership with Facebook.)
We wanted to know if there was any truth in the idea that the CDC was suppressing its test because it is faulty and cannot distinguish one virus from another. We therefore consulted several experts in laboratory tests.
The real reason for the withdrawal of the EUA application
The first Facebook post we referenced cited and was linked to a July 21 CDC lab alert that informed labs that as of December 31, the agency would withdraw its emergency use authorization request for the novel coronavirus CDC 2019 (2019-nCoV) in real-time reverse Transcriptase (RT) -PCR diagnostic panel or, for short, the CDC 2019-nCoV RT-PCR.
It is standard practice for the Food and Drug Administration to issue temporary emergency use authorizations for tests and other medical products that have not yet gone through the full FDA approval process but are to be used. in an emergency to diagnose, treat or prevent serious illnesses.
The FDA issued the EUA for the CDC’s RT-PCR 2019-nCoV in February 2020. At that time, no other tests were available in the United States to determine if anyone had COVID.
But it’s important to remember that what the CDC developed and submitted for its EUA application was not a tangible product but rather a protocol on how to test for COVID, said Susan Whittier, professor of pathology and of Cell Biology at Columbia University Irving Medical Center. This means that the CDC wrote instructions specifying which reagents were needed to test lab samples for the presence of the COVID virus. The CDC does not distribute COVID tests.
“It’s not like they have a test that labs can buy. We borrow their protocol and use the reagents they say,” said Whittier, who recently retired as director of the Columbia Clinical Microbiology Laboratory. Thus, the withdrawal of the EUA request “simply means that the protocol will no longer be available”.
In the lab alert, the CDC said it was withdrawing EUA’s request because, rather than just testing for the COVID virus, it wants labs to test people for multiple viruses simultaneously, using what one calls “a multiplexed method”. CDC’s RT-PCR 2019-nCoV panel only tests for COVID-19.
“Such tests can make it easier to continue testing for influenza and SARS-CoV-2 and can save time and resources as influenza season approaches,” noted the alert regarding the multiplexed method.
Dr Christopher Polage, associate professor of pathology at Duke University, said his take on the CDC’s message is that, because flu season is on the horizon, a patient may have respiratory symptoms. that could be attributed to COVID-19 or the flu. Laboratories should start testing for both COVID and various influenza viruses.
But the lab alert doesn’t mean the CDC’s test can’t tell the difference between COVID-19 and the flu.
In fact, the CDC’s test was developed to look for the presence of a nucleic acid found only in the COVID virus, said Kelly Wroblewski, director of infectious disease programs at the Association of Public Health Laboratories.
“It is not remotely correct that the CDC test does not differentiate between influenza and SARS-CoV-2. It does not detect influenza. It only detects SARS-CoV-2,” said Wroblewski. “If the flu and COVID are both circulating, you will only be able to detect SARS-CoV-2 and not the flu. “
The way the PCR test (or any other PCR test) works, Wroblewski said, is that primers, which are small pieces of genetic material, are used to identify specific viruses. In this case, the primer is designed to identify a nucleic acid found only in the COVID virus.
If the COVID virus is present in the sample, the primer will attach to the nucleic acid of the virus and make many copies of it. A chemical in the test will then fluoresce, which the polymerase chain reaction, or PCR, machine will interpret as a positive result. If the COVID virus is not present, the bait will have nothing to attach to.
When asked about the CDC’s withdrawal from its EUA request, FDA spokesperson Jim McKinney told us PCR tests are considered the “gold standard” for diagnosing COVID. He gave us data that illustrated the specificity and exclusivity of the CDC test. These data show that test results came back negative for samples containing similar viruses, including different types of influenza and other coronaviruses.
All of this means that the CDC’s test would not mistakenly detect influenza viruses. So the claims from Facebook posts that the test cannot tell the difference between COVID and the flu are patently false.
Even though the CDC withdraws its EUA request for this specific test, Wroblewski pointed out, it still has an EUA for a second PCR test, a multiplex that simultaneously tests for COVID and influenza types A and B.
The FDA has issued EUAs to numerous labs and testing companies for hundreds of COVID tests that use the same PCR technology as the CDC – which experts say has essentially rendered the CDC’s testing protocol moot because similar tests will always be available.
So, while it is true that the CDC is withdrawing its EUA request for its test that only tests for COVID, it is not for the reasons given by the Facebook posts. The claim that the number of COVID cases was inflated because the test was faulty and counted influenza cases as COVID cases is false.
“They didn’t take the EUA out because the test wasn’t working,” Whittier said. “They just wanted people to look for other viruses as well.”
Polage agreed.
“The CDC is withdrawing its test” from the market “as a move to encourage laboratories to use tests that include reagents (primers and probes) for SARS-CoV-2 and influenza so that suppliers, laboratories, states and the CDC have better data this fall and winter to estimate how many clinical flu-like syndromes are due to SARS-CoV-2 and how many are due to seasonal flu, “Polage said in an email.
Our decision
Social media posts claimed the CDC was revoking its emergency use authorization request for its COVID test because it could not tell the difference between the COVID virus and influenza viruses. While the CDC is withdrawing its EUA application for the 2019-nCoV RT-PCR assay, it’s not because the assay is flawed.
Rather, it’s because the agency is concerned that as flu season approaches, patients with symptoms of respiratory illness should be screened for both the flu and COVID. Patients should not be tested for COVID alone, as flu cases could be missed.
Statements made in these Facebook posts are not accurate. We assess this claim as false.
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