The Food and Drug Administration has issued its first authorization for a COVID-19 test that looks for antibodies in the blood, rather than viruses in the nose or throat. Although the antibody approach means that this test will have limitations, it is an important tool that could help in the response to the pandemic.
The test is produced by the biotechnology company Cellex. Healthcare providers must draw blood from a patient’s vein for testing, and this can only be done in certified laboratories – not a doctor’s office. It takes 15 to 20 minutes to get a result.
When a person is first infected with a virus, their immune system begins to produce antibodies specific to that virus. Checking if someone has antibodies specific to the coronavirus is good evidence that they have been infected. However, the body does not start producing them immediately, and they may not appear until someone’s disease has run its course. As a result, antibody-based tests can tell doctors if someone has ever had COVID-19, but they’re not as good at testing if the patient currently has COVID-19.
However, FDA clearance indicates that the agency believes the benefits of having the test available outweigh the risks. “It is reasonable to believe that your product may be effective in diagnosing COVID-19,” the agency wrote in the letter, which authorized the test for emergency use.
The FDA already allowed companies to do and distribute antibody tests for COVID-19 without official authorization. However, without approval, they could not pretend that their test could diagnose disease.
Even if they are not excellent diagnoses, antibody tests are essential in responding to the pandemic. They would help determine who has ever been sick – whether or not they have significant symptoms – and, therefore, who is likely to be immune enough to the virus to move around the world safely. They will also help public health officials understand the proportion of the population infected with coronavirus. Dozens of companies are working to develop antibody tests, as are researchers at the Centers for Disease Control and Prevention.
The United States has struggled to speed up COVID-19 testing, and it is still difficult for people to access the tests. Although there have been more than a million tests done in the United States, a milestone that President Trump highlighted earlier this week, the per capita test rate is still far behind other countries. An easily accessible antibody test would give people who have not been able to get tested while sick a chance to find out if they have actually had COVID-19.