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The FDA has approved a blood test that will determine whether a person has been infected by COVID-19, the agency said Thursday morning.

“We’re going to announce today, our first approval of a serology test that will, in laboratories, allow the labs to determine exposure in the antibodies,” FDA Commissioner Dr. Stephen Hahn said on CBS News Radio.

These serology tests can effectively identify past coronavirus infections, but are less successful at identifying recent ones, CNN reported.

The authorized test, from manufacturer Cellex Inc., requires blood to be collected through a vein and can only be performed in a certified lab, according to the report.

Because antibodies can take a while to develop, the FDA has previously warned against using such tests to definitively diagnose COVID-19, according to the report.

But it has issued an Emergency Use Authorization for this test, indicating that the benefits outweigh the risks.

“Based on the totality of scientific evidence available to FDA, it is reasonable to believe that your product may be effective in diagnosing COVID-19,” FDA chief scientist Denise M. Hinton said in a Wednesday letter to James X. Li, the CEO of Cellex.

“The known and potential benefits of your product when used for diagnosing COVID-19, outweigh the known and potential risks of your product.”

Serology tests can help officials grasp how prevalent the virus is — allowing them to identify people who may have been infected before but showed little to no symptoms, CNN reported.