- FDA has alerted clinical laboratory staff and healthcare providers about the risk of false positive results with two Abbott Laboratories tests for COVID-19.
- The kits can report false positives when wells in the assay reagent tray that contain positive samples overflow and contaminate neighboring specimens. FDA is advising users to view positive results as "presumptive" and consider retesting using another product.
- Abbott's status as a supplier to clinical laboratories means the problem will affect multiple other organizations. Curative switched to Abbott tests earlier this year in response to a risk of false results linked to its own product.
Abbott's tests run on its Alinity automated molecular diagnostics analyzer. CEO Robert Ford picked out the rollout of the analyzer as a driver of growth in Abbott's underlying diagnostics business in July. Ford previously said launching the platform with the COVID-19 test "helped jumpstart demand."
Curative is among the companies to adopt the platform. After receiving reports of false results from its own test, Curative asked FDA to revoke its EUA and struck a deal with Abbott to access the Alinity tests for COVID-19 and the set of respiratory pathogens.
Abbott first received FDA emergency use authorization for its Alinity m SARS-CoV-2 AMP test in May 2020. Since then, FDA has granted revisions to the EUA, most recently in August, and cleared Abbott to sell a version of Alinity that tests for SARS-CoV-2, two types of influenza and respiratory syncytial virus. The alert about false positives applies to both Alinity products.
"The false positive results may be related to current mixing parameters of the PCR reaction mixture that may result in potential overflow that could carry over into neighboring wells in the assay reagent tray. Overflow into the wells of true negative samples that are positioned near positive samples in the assay tray could produce false positive results," FDA wrote in its alert.
FDA used the warning to make two recommendations to users of Alinity tests. The agency is advising clinical laboratories and healthcare professionals to view any positive results delivered by Alinity as "presumptive."
The advice extends to positive results issued in the past. FDA is asking users to consider "retesting positive patient specimens performed in the last two weeks with an alternate authorized test." For older positive test findings, dating back as far as June, FDA is advising users to consider telling the patient their result may have been false. FDA is now working with Abbott to resolve the issues.