The U.S. Food and Drug Administration is telling people to stop using a certain brand of rapid COVID-19 tests due to the possibility they could give false results.

The tests – Empowered Diagnostics CovClear COVID-19 Rapid Antigen Test and ImmunoPass COVID-19 Neutralizing Antibody Rapid Test – are labeled as indicating they are authorized by the FDA but they have not been authorized, cleared or approved by the agency, the FDA said.

“The FDA is concerned about the potentially higher risk of false results when using unauthorized tests,” the agency said, adding it has issued a Class I recall, the most serious type.

The CovClear tests used a nasal swab sample to detect coronavirus. The ImmunoPass version uses a fingerstick blood sample designed to detect antibodies from a previous infection. Both tests could possibly give false negative results, leading to lack of treatment or unintentional spread of the virus.

If you have used the tests less than two weeks ago, the FDA recommends retaking one using an FDA-authorized rapid kit. If the test was performed more than two weeks ago and there is no reason to suspect a current COVID-19 infection, it’s not necessary to retest.

People who have used the test and believe they have had a problem should report it to the MedWatch Voluntary Reporting Form.