False positive results possible with Roche test

March 15, 2021

The U.S. Food and Drug Administration (FDA) announced that false positive results can occur with the Roche Molecular Systems cobas SARS-CoV-2 & Influenza A/B Nucleic Acid Test for use on the cobas Liat System, according to a news release from the FDA.

The FDA said the false positive results may be related to two issues observed by Roche.

Roche said that the assay tubes may sporadically leak, causing an obstructed optical path in the Liat analyzer, producing abnormal PCR growth curves. This could lead to invalid or erroneous positive results, particularly for the Flu B test. If a tube leak occurs, later testing runs may have an increased likelihood of false positive Flu B results.

Roche also determined that abnormal PCR cycling in the reaction tubes may also produce abnormal PCR growth curves, leading to erroneous results. The issue is sporadic and may be caused by multiple factors happening at the same time, such as hardware positioning, volume movement, and curve interpretation. This issue may cause false positive results for multiple analytes (Influenza A, Influenza B and/or SARS-CoV-2) in a single testing run.

The FDA recommends users of the cobas SARS-CoV-2 & Influenza A/B Nucleic Acid Test for use on the cobas Liat System:

·        Watch out for unexpected clusters of positive Flu B results, as this may indicate the cobas Liat System has experienced a tube leak.

·         Repeat tests when two or three analytes are positive. Different results on the repeat test may indicate abnormal PCR cycling.

·         Stop using the cobas Liat System and contact Roche if you suspect either of these two issues has occurred.

The FDA issued an emergency use authorization (EUA) for the test on September 14, 2020 and granted revisions to the EUA in September and December 2020.

Visit the FDA for more news