On July 21st, 2021, a Lab Alert issued by the U.S. Centers for Disease Control and Prevention (CDC)’s Center for Surveillance, Epidemiology, and Laboratory Systems announced that the CDC would be withdrawing its request for emergency use authorization for its COVID-19 PCR diagnostic test after December 2021. Claims regarding the misuse of the COVID-19 PCR test have been circulating for quite some time. This Lab Alert has rekindled these claims, using it as validation that the test is inaccurate. Many are also citing this statement in the Lab Alert: “CDC encourages laboratories to consider adoption of a multiplexed method that can facilitate detection and differentiation of SARS-CoV-2 and influenza viruses” and using it as validation that the test cannot differentiate the difference between SARS-CoV-2 and the flu virus.
It should be noted that the Lab Alert only pertains to the CDC’s own COVID-19 diagnostic PCR test. A spokesperson from the CDC has explained that the performance of the CDC’s RT-PCR test for detecting COVID-19 didn’t suffer from any problems. They have withdrawn their RT-PCR test because there are better tests that have since been developed which can process more samples within a given time. There are also tests that can now detect more than one pathogen. The COVID-19 PCR test specifically detects the presence of the genetic material from SARS-CoV-2. The genetic sequence of the flu virus is different from the SARS-CoV-2 virus and wouldn’t be detected by a COVID-19 PCR test.
Dr. Stephen R. Master, AACC President, Chief, Division of Laboratory Medicine, Children’s Hospital of Philadelphia has this to say...
The CDC has issued an alert stating that after December 31, 2021, it will withdraw its request for FDA emergency use authorization (EUA) for its SARS-CoV-2 test, which uses PCR technology (the gold standard for detecting SARS-CoV-2). This has led to the circulation of posts online falsely claiming that the CDC’s test was mistaking the flu virus for the SARS-CoV-2 virus and that FDA has revoked CDC’s EUA as a result.
Neither of these claims is true. The FDA has not revoked the CDC’s EUA. Rather, the CDC has decided to voluntarily withdraw it for a couple of reasons. First, it is no longer necessary. The CDC’s test initially received an EUA when no other SARS-CoV-2 tests were available in the U.S. Now that hundreds of SARS-CoV-2 PCR tests have received EUAs and are widely available, the CDC’s test is no longer needed to fill an unmet testing need. In retiring the test, the CDC plans to shift resources towards public health surveillance and other pandemic response activities that are critical for it to maintain. Second, the CDC is promoting the use of tests that can detect and generate a result for both flu and SARS-CoV-2 as a cost-efficient approach to testing. The CDC has a separate EUA for such a test—one that detects and distinguishes between SARS-CoV-2, influenza A, and influenza B—that it will be maintaining. The CDC and other public health laboratories will be using this test so they can simultaneously monitor flu activity in addition to SARS-CoV-2 going forward.
The claim that the CDC’s test was misidentifying flu cases as COVID-19 cases is false. The CDC’s test for SARS-CoV-2 detects a genetic sequence found only in the SARS-CoV-2 virus and does not detect flu. Patients sick with the flu would have a negative result for SARS-CoV-2 with the test the CDC is discontinuing. However, these patients will have a negative result for SARS-CoV-2 and a positive result for flu with the test the CDC is maintaining. This allows the CDC to provide additional diagnostic information and collect important public health data about the amount of flu circulating without additional cost when performing testing. For this reason, the CDC will be using this combination test going forward.