CDC Says Possibly ‘Less Than Half’ Of Positive Antibody Tests Are Correct

There are two kinds of Covid-19 tests: molecular diagnostic tests, which can identify people with active infections, even when they have no symptoms, and antibody, or serology, tests, which indicate that a person was infected at some point in the past.

According to Christopher Farnsworth, an instructor of pathology and immunology at Washington University School of Medicine, “antibody testing is really helpful in monitoring how widely a virus has spread within a community. Such testing could help determine how many people have recovered from the virus, even if they never had symptoms.”

Thus, antibody tests could potentially play a very important role if and when schools should reopen, or when professional sports will return.

However, the CDC has acknowledged that antibody testing can frequently be inaccurate, especially in populations where there is a low prevalence of the coronavirus. 

In fact, under certain scenarios, “less than half of those testing positive will truly have antibodies,” the agency says.

This is particularly dangerous because it could lead to individuals believing they have been infected with the coronavirus, and acting as if they have immunity, when that is not the case.

As a result, the CDC advises that antibody test results should not be used to make decisions related to schools, dormitories, or correctional facilities, and that testing shouldn’t be used to determine immune status in individuals.