At-home COVID-19 tests are considered a critical part of America’s response to the pandemic because they help alleviate strain on health care systems and pharmacies during surges in cases. However, officials warned against the use of unauthorized tests out of concerns that the results aren’t accurate, and the FDA advised people to throw out STANDARD Q COVID-19 Ag Home Test kits because it only provides an “initial screening test result.”

The test kit, created by SD Biosensor, Inc., was not authorized, cleared or approved by the FDA for use in COVID-19 testing. Given that it hasn’t been approved, the FDA said anyone who used the test were “strongly encouraged” to retest with an FDA-authorized test.

Sixteen of the FDA-authorized at-home COVID-19 tests are considered “single target” tests. This means they’re designed to only detect only one antigen target, according to the FDA. This makes them more susceptible to inaccuracies as the virus mutates, and it’s possible they won’t detect new variants.

Those 16 single-target tests are:

InteliSwab COVID-19 Rapid Test RXQuickVue At-Home COVID-19 TestBinaxNOW COVID-19 Ag Card Home TestBinaxNOW COVID-19 Ag Card 2 Home TestSCoV-2 Ag Detect Rapid Self-TestCareStart COVID-19 Antigen Home TestMaximBio ClearDetect COVID-19 Antigen Home TestBinaxNOW COVID-19 Antigen Self TestCOVID-19 At Home Test (SD Biosensor, Inc. )CLINITEST Rapid COVID-19 Antigen Self-TestiHealth COVID-19 Antigen Rapid TestQuickVue At-Home OTC COVID-19 TestInteliSwab COVID-19 Rapid TestFlowflex COVID-19 Antigen Home TestEllume COVID-19 Home TestBD Veritor At-Home COVID-19 Test

Currently, there is only one FDA-authorized at-home COVID-19 test that is considered a “multiple target” test. The Celltrion DiaTrust COVID-19 Ag Home Test is designed to detect both a section of the spike protein and a section of the nucleocapsid protein.

At-home COVID-19 tests gained popularity over the holidays as people planned to gather and the Omicron surge made it more difficult to get in-person testing appointments. Identifying infections early is one of the best ways to prevent COVID-19 from spreading and the Biden administration launched a program to send four free COVID-19 rapid test kits to each home in the United States to help expand access.

There are some concerns about the accuracy of at-home tests. While they’re considered reliable for those who have symptoms, some tests may return a false negative if a person hasn’t developed symptoms yet. The time a person takes the test and weather conditions during transportation could affect a person’s results, as well. So, officials have cautioned people against using a negative test as a free pass.

It’s unclear how many people may have used or were planning to use a Standard Q COVID-19 Ag Home Test because the FDA has no “known distribution” of the tests directly to consumers.