The Food and
Drug Administration in the United States has indicated that rapid antigen tests
for COVID-19 might be less effective at detecting the Omicron variant.

Early data
suggest that COVID-19 antigen tests “do detect the Omicron variant but may
have reduced sensitivity,” the FDA noted in a statement posted this week
on its website.

The FDA is
working with the National Institutes of Health’s Rapid Acceleration of
Diagnostics (RADx) initiative to assess the performance of antigen tests with
patient samples that have the Omicron variant.

The
potential for antigen tests to be less sensitive for the Omicron variant
emerged in tests using patient samples containing live virus, “which
represents the best way to evaluate true test performance in the
short-term,” the FDA explained.

Initial
laboratory tests using heat-activated (killed) virus samples found that antigen
tests were able to detect the Omicron variant.

“It is
important to note that these laboratory data are not a replacement for clinical
study evaluations using patient samples with live virus, which are ongoing. The
FDA and RADx are continuing to further evaluate the performance of antigen
tests using patient samples with live virus,” the FDA added.

The agency
continues to recommend use of antigen tests as directed in the authorized labelling
and in accordance with the instructions included with the tests.

They note
that antigen tests are generally less sensitive and less likely to pick up very
early infections compared to molecular tests.

The FDA
continues to recommend that an individual with a negative antigen test who has
symptoms or a high likelihood of infection due to exposure follow up with a
molecular test to determine if they have COVID-19.

An individual
with a positive antigen test should self-isolate and
seek follow-up care with a healthcare provider to determine the next steps.

SOURCE: https://www.medscape.com/viewarticle/965766