As the omicron variant continues to spread across the globe, FDA and test manufacturers have scrambled to assess whether the performance of current COVID-19 diagnostics are affected by its viral mutations.
Here's what we know so far:
Major manufacturers of both polymerase chain reaction and rapid antigen tests, including Abbott Laboratories, Becton Dickinson, Quidel and Siemens Healthineers, have said their diagnostics can detect omicron.
However, FDA on Dec. 28 said early data suggests that while antigen tests do detect the omicron variant, some may have reduced sensitivity based on preliminary studies by the National Institutes of Health's Rapid Acceleration of Diagnostics (RADx) program which evaluated their performance using patient samples containing live virus.
FDA did not say which specific companies' tests were analyzed by RADx.
The agency noted such live virus samples are the "best way to evaluate true test performance in the short-term." Prior to completing these live virus tests, RADx conducted initial laboratory tests using heat-inactivated samples for some of the currently available antigen tests, which were able to detect omicron with similar performance when detecting other variants, according to FDA.
While the majority of commercially-available PCR tests are unaffected by omicron, FDA's analysis to date has identified certain EUA-authorized molecular diagnostics whose performance may be impacted by mutations in the variant.
FDA earlier this month warned that molecular tests from Applied DNA Sciences, Meridian Bioscience and Tide Laboratories are not able to detect omicron, causing false negative results, and should not be used by clinical laboratory staff and healthcare providers.
However, on Dec. 27, FDA issued an update in which it said Tide's test has been modified and is now expected to detect the omicron variant.
Omicron contains mutations to the spike protein and if tests rely on the spike gene to detect the virus it can cause false negative results. In the case of Applied DNA Sciences' Linea COVID-19 Assay Kit, the test has two viral targets on the SARS-CoV-2 genome and both cover the portions of the S-gene where these mutations occur and are not able to detect omicron.
Meridian Bioscience offers a single-target test that is not able to detect omicron due to a nine-nucleotide deletion in the N-gene, which is the genetic target of their diagnostic.
Tim Stenzel, director of the FDA's Office of In Vitro Diagnostics and Radiological Health, told test developers during a Dec. 15 virtual town hall that the agency will continue to focus efforts on assessing both molecular and antigen tests and provide updates to its website as new information emerges on omicron's impact on testing.
"We believe omicron is going to be a significant variant in the U.S. in very short order," Stenzel warned.
Meanwhile, in efforts to combat rising COVID-19 cases heading into the winter and the emergence of omicron, the Biden administration ordered private insurers to cover at-home COVID-19 testing. Although, experts have criticized the move for not going far enough.