FDA has alerted healthcare professionals to the risk of false positives from Roche’s combined influenza-COVID-19 test.
The PCR test, which runs on the cobas Liat System, can sporadically report false positives for influenza B or all three viruses it checks for, possibly due to two issues seen by the Swiss medtech giant.
FDA is asking users who suspect their systems are suffering from either issue to stop running tests on them and contact Roche.
Roche’s SARS-CoV-2 & Influenza A/B Nucleic Acid Test is a PCR product that checks for COVID-19 and two types of flu. However, Roche has identified two issues with the test that may explain reports of false positives.
One issue relates to sporadic leaks from the assay tubes. Roche’s analysis suggests the leaks can block the optical path in the Liat analyzer and, in doing so, cause erroneous results. The leaks mainly lead to false positives for influenza B.
The second issue stems from abnormal cycling in the reaction tubes. Roche found the abnormal cycling happens sporadically and may be due to multiple, simultaneous factors, including hardware positioning and volume movement. Again, the issue can manifest in erroneous results, in this case false positives for multiple viruses in a single testing run.
A spokesperson for Roche set out the situation.
"Specifically, we are addressing some false positive results, particularly for the Influenza B target, that have occurred sporadically. We are conducting an in-depth investigation to fully understand the cause and to determine next steps. We proactively reported these events to the FDA and are working very closely with the agency."
FDA is advising users of the test to monitor for clusters of positive influenza B results that may be a sign that an assay tube has leaked. Equally, the agency wants users to treat tests that are positive for two or three of the viruses with caution. If a repeat test yields different results, the Roche system may have suffered from abnormal PCR cycling. Users who suspect either issue has occurred should stop using the system and contact Roche.
Roche in September touted its test as an important moment in preparations for a potential surge in COVID-19 and flu over the winter months. Healthcare professionals could, for the first time, use a fully automated high throughput system to differentiate between COVID-19 and flu, enabling them to choose the right treatment for conditions that cause similar symptoms.
In the end, historically low levels of influenza rendered the concern about differentiating between COVID-19 and flu moot. Quidel said influenza levels were too low to generate more orders for its combination kit and Roche, a larger business that provides less granular detail about its diagnostics, may face similar dynamics.