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Abbott gets emergency FDA approval for antibody test that detects recent COVID-19 infections

Abbott’s latest antibody test — meant to show whether a person has recently had COVID-19 — has gained emergency use authorization from the U.S. Food and Drug Administration.

The blood test detects a type of antibody, called IgM, that’s present after a person has been recently infected with COVID-19, Abbott said in a news release.

It’s the second antibody test made by north suburban-based Abbott to gain emergency use authorization, in which the FDA allows the use of unapproved medical products to diagnose, treat, or prevent serious or life-threatening diseases when certain criteria are met.

Abbott’s first test looks for a different type of antibody called IgG that’s longer-lasting in the body after infection. That test can help show whether someone has recovered from the virus and can help with contact tracing, according to the company.

The new test is more useful when it comes to finding recent infections, which can be helpful for doctors trying to determine where a patient is in the recovery process and if treatment or isolation is appropriate, Abbott said.

IgM often becomes undetectable weeks to months after a person becomes infected, whereas IgG may be detectable for months or years, according to the Centers for Disease Control and Prevention.

The new test is 99% accurate when it comes to negative results and 95% accurate for positive results 15 days after a patient experiences symptoms, Abbott said.

A number of other IgM and IgG tests from other companies have already gained emergency authorization.

IgM tests can be useful when someone receives a positive result, said Dr. Elizabeth McNally, director of the Center for Genetic Medicine at Northwestern University’s Feinberg School of Medicine. It might be helpful, for example, for people who recently felt ill but didn’t get COVID-19 tests at the time, but want to find out if that’s what they had. It could be helpful for better understanding people recovering from the illness, she said.

But care must be taken not to read too much into negative results, she said. A person might test negative because the IgM antibodies have already come and gone.

IgM can be highly variable between individuals, McNally said, with some people producing the antibody within a day of becoming ill and others taking seven days. It doesn’t last in the body very long, she said.

“The challenging part of IgM is it’s transient,” McNally said. “It’s a little unpredictable about when it comes up and goes down, and it’s incredibly variable.”

The new test is the seventh COVID-19-related test made by Abbott to gain emergency use authorization.