25 Percent of CDC Coronavirus Test Kits Are Inaccurate, Study Finds

Even if you were tested by a doctor, your COVID test results may have been wrong.

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Coronavirus testing has been a hot-button issue since the beginning of the pandemic. First, there weren't enough coronavirus tests to go around. Now, a new issue has emerged—just how accurate the tests people are getting actually are. According to a July 17 study published in the International Journal of Geriatrics and Rehabilitation, 25 percent of nucleic acid coronavirus tests distributed by the Centers for Disease Control and Prevention (CDC) provided inaccurate results.

The study's lead author, Sin Hang Lee, MD, director of Milford Molecular Diagnostics Laboratory, found that the testing kits gave a 30 percent false-positive rate and a 20 percent false-negative rate. According to the report, "2 false negatives and 3 false positives were found in 20 reference samples," meaning 25 of the total tests studied yielded inaccurate results.

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To determine these false-positive and false-negative rates, the Connecticut State Department of Public Health Microbiology Laboratory provided Lee 20 tests, which were then re-tested using his own methodology, which examines samples on a cellular level, rather than just testing fluid with no cellular matter from potentially infected oral and nasal secretions.

While the results of Lee's testing may be alarming, they also pointed to yet another discovery: new mutations of the virus. Using Sanger sequencing—a method of determining nucleotide (a building block of DNA) sequences within DNA samples—two tests that initially provided false-negatives and one test that yielded a positive result were actually found to be positive for coronavirus and a mutation of the virus, meaning two variants of the virus can simultaneously infect one person.

A close up of a technician wearing blue gloves placing a drop of blood on a COVID-19 antibody test strip
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So, what does this mean for coronavirus testing going forward? Lee says that the level of inaccurate test results should prompt more in-depth testing methods, especially among vulnerable populations.

"Long-term care facilities with exceptionally high COVID-19 death tolls among their residents and hospitals with active nose-and-throat surgery departments may need to install an extremely sensitive and highly accurate Sanger sequencing-based test," Lee explained.

However, it's not just the test you use that may be contributing to inaccurate results—when you get tested is important, too. According to a May 2020 study published in the Annals of Internal Medicine, getting tested the day a person is infected with coronavirus will likely yield a 100 percent false-negative rate; by day 8 after becoming infected, however, that rate drops to just 20 percent. And if you want to know your coronavirus status, This Is the Type of COVID-19 Test You Should Be Asking For.

Update: An earlier version of this article inaccurately stated that Lee's study found that 50 percent of CDC coronavirus test kits are inaccurate. The article has since been corrected.

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