FDA warns Abbott Alinity PCR COVID test results may only be 'presumptive' due to risk of false positives

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Abbott has received emergency authorizations from the FDA for two of its Alinity m PCR assays: one that tests only for COVID-19 and another that can detect the coronavirus alongside respiratory syncytial virus and influenza A and B. (Abbott)

The FDA urged clinical laboratories and healthcare providers to retest any patients who have recently received a positive result from two of Abbott’s PCR COVID-19 assays after identifying a heightened risk of false positives associated with the testing mechanism.

The agency’s safety alert concerns assays conducted using Abbott’s Alinity m molecular diagnostics analyzer: one that tests only for COVID and another that can detect the coronavirus alongside respiratory syncytial virus and influenza A and B. The former received its initial emergency use authorization from the FDA in May 2020—an authorization that was revised and upheld as recently as last month—while the multiuse test was authorized in March of this year. Both tests are authorized for use only in clinical labs certified to perform moderate- or high-complexity tests.

According to the FDA, because of the amount of PCR reaction mixture required to prepare samples for testing with the Alinity m device, some of the samples may overflow into nearby wells in the assay reagent tray during mixing. If that happens and a positive sample leaks into the well of a true negative sample, it could result in a false positive. (The reverse isn’t a concern, because the addition of a small amount of a negative sample to a positive one wouldn’t negate the presence of the coronavirus.)

RELATED: CDC study says Abbott's rapid COVID-19 antigen test may miss two-thirds of asymptomatic cases

Abbott and the FDA are currently working on developing a solution to this issue. In the meantime, the agency is recommending all positive results returned by the two Alinity m tests be considered “presumptive.”

The FDA suggested that labs and healthcare providers retest anyone who has recently tested positive with either assay using a different authorized test. They may also consider contacting all patients who have tested positive with the Alinity m assays since this past June to let them know they may have received a false positive result.

The agency is asking testing providers to report any further difficulties with conducting the tests—or any adverse events they know or suspect are linked to them—directly to the FDA.

RELATED: Quidel recalls a year’s worth of COVID-19 PCR tests over ‘significant risk’ of false negatives

Though the FDA has made a habit of cracking down on inaccuracies in COVID-19 tests through the pandemic, it typically has been spurred by an increased risk of false negatives rather than positives.

Abbott’s own ID NOW rapid molecular tests and BinaxNow rapid antigen tests, for example, have both come under fire for what researchers say are higher-than-normal rates of false negatives. Last year, a handful of studies demonstrated the ID NOW kit’s tendency to overlook the virus, with one New York University study finding it missed almost half of the positive samples detected by another company’s test.

Then, at the beginning of this year, a group of Centers for Disease Control and Prevention researchers published a study showing that the card-based BinaxNow test may miss up to two-thirds of asymptomatic cases of COVID.

But Abbott’s not alone: In June, the FDA called for an immediate halt to the use of Innova Medical Group’s rapid antigen tests after identifying “significant concerns” with their accuracy, going so far as to suggest that the public “destroy the tests by placing them in the trash.”

The following month, Quidel issued a voluntary recall of a year’s worth of its Lyra PCR assays. The Class I recall was initiated after the company discovered that the tests posed a “significant risk” of returning false negatives on samples that, counterintuitively, contain relatively high amounts of the virus.