A month after Abbott issued a safety notice describing a defect that could cause some of its COVID-19 tests to return false positive results, the FDA has upgraded the issue into a Class I recall.
In early September, Abbott notified its healthcare provider and laboratory customers that it had identified an issue with the software used by special lab processing equipment to prepare swab samples for testing with its Alinity m SARS-CoV-2 and Alinity m Resp-4-Plex assays.
The software automates the mixing of chemicals with the patient samples. Under certain mixing parameters, enough liquid may be added to a sample to cause it to overflow into neighboring wells in the processing tray. That could result in mistakenly positive results if a COVID-positive sample overflows into a nearby negative one.
Abbott’s notice and a subsequent letter sent by the FDA to healthcare providers advised customers to consider all positive results returned by the two affected tests to be “presumptive.” They recommended that anyone who had received a positive result in recent weeks be immediately retested with another diagnostic. Additionally, they warned patients who received positive results from the test kits in past months to keep in mind that they may not have actually had the coronavirus and so should not presume to be protected by antibodies.
The FDA’s latest update isn’t a recall in the traditional sense of the term. Rather than asking customers to return the affected tests, it notes that the automated software in the lab equipment required to process those tests is in the process of being corrected.
The Class I label indicates that the issue is a serious one, with the FDA identifying a high risk of causing serious adverse events or death—though none have yet been reported in connection with the software defect.
Some potential risks of false positives include unnecessary treatments or isolation, delayed diagnosis of the actual cause of a test-taker’s illness and the continued spread of the virus if people with seemingly positive results are quarantined together, the agency said.
According to the recall notice, 187 software installations are undergoing corrections. Altogether, those programs are responsible for analyzing the results of more than 10 million already distributed tests: more than 9.9 million Alinity m SARS-CoV-2 tests and just over 48,000 of the Resp-4-Plex assays, which test for respiratory syncytial virus and influenza A and B as well as the coronavirus.
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A handful of other COVID tests have also been subject to FDA recalls, though most, like Quidel’s July announcement, were because of a heightened risk of false negatives rather than false positives.
Just this month, however, another test was found to potentially send back incorrectly positive results. The FDA offered up its Class I label last week to Ellume’s voluntary recall of its over-the-counter COVID-19 Home Test kits, caused by an undisclosed manufacturing issue that was found to return more false positives than had been observed in initial clinical testing.