Roche’s Cobas COVID-19/flu combo test runs on its Cobas Liat system. According to an FDA release, the false-positives may be related to two issues observed by the company.
The company observed that the assay tubes might sporadically leak and cause an obstructed optical path in the Liat analyzer, which would, in turn, produce abnormal PCR growth curves, potentially leading to invalid or erroneous positive results, particularly with Flu B.
Additionally, abnormal PCR cycling in the reaction may also produce abnormal PCR growth curves, leading to erroneous results. Multiple factors may cause this issue, including hardware positioning, volume movement and curve interpretation.
The FDA recommended that users of the Cobas combo test on the Cobas Liat system monitor for unexpected clusters of positive Flu B results, as it may indicate that the system experienced a leak.
On top of that, the FDA said to repeat tests when two or three analytes are positive, as different results may indicate abnormal PCR cycling. Users should stop using the system altogether and contact Roche if they suspect either of those two issues has occurred.
Roche’s test received FDA emergency use authorization (EUA) in September 2020 and garnered revisions to the EUA again that month and later in December 2020. The company is working with the FDA to resolve the issues.