McGowan Institute for Regenerative Medicine faculty member Alan Wells, MD, DMS, Thomas J. Gill III Professor of Pathology and the Executive Vice-Chairman of the Department of Pathology at the University of Pittsburgh, recently spoke with Michael Ollove, Staff Writer, Stateline, an initiative of The Pew Charitable Trusts, about COVID antibody tests. Talk of the need for COVID-19 booster shots has prompted many Americans to seek these tests.
In most cases, however, getting an antibody test to determine immunity is a fool’s errand, infectious disease doctors agree. The tests for antibodies, also known as serology tests, do not provide the answers that most people are seeking.
Both the federal Centers for Disease Control and Prevention and the Food and Drug Administration advise against using antibody tests to determine one’s level of immunity against COVID-19. So does the Infectious Disease Society of America, which represents infectious disease specialists.
While some states, including Maryland and South Carolina, are conducting targeted antibody testing for specific purposes, no state is promoting the tests’ use for residents to determine whether they have sufficient immunity or need a booster shot.
The tests might indicate the presence or even the level of COVID-19-fighting antibodies in the bloodstream, but scientists don’t yet know what number of antibodies provide protection from COVID-19. Antibodies are protein molecules the immune system produces to neutralize viruses or bacteria that have entered the body.
Antibody levels do help health care providers establish whether a patient has immunity against other, more familiar infectious diseases, such as measles and hepatitis A and B. But doctors say our relatively short experience with COVID-19 hasn’t yet provided the same information.
Testing for COVID-19 antibodies has some benefits—especially for determining whether someone with COVID-like symptoms had an earlier, undetected COVID-19 infection—but not for the reasons many are seeking the tests.
“Doctors are ordering antibody tests for people who are worried about waning immunity, but I see that as problematic,” said Dr. Wells, director of clinical labs at UPMC. “For a normal person, knowing your level eight months later [after their initial vaccine dosages] is of relatively little value.”
In general, the more antibodies, the better, Dr. Wells said. But even with a low level of antibodies months after exposure or receiving a vaccine, the body can mount a stout defense against the virus by generating new antibodies in response to a fresh infection. “There is more to your immune response than antibody levels,” said Dr. Wells.
Dr. Wells said the UPMC hospital, like others, has had a big increase in requests for antibody tests in recent weeks, though he recommends to his colleagues that they use them judiciously.
Another problem with COVID-19 antibody tests, doctors say, is that they are not standardized, so values associated with antibody tests in one version might not be the same as another.
Without knowing what level of antibodies provides immunity or the parameters—especially the timing—of testing vaccinated people, such a measure may not provide the assurance its sponsors suggested. But Dr. Wells added that the idea is not without merit, because higher levels of antibodies do correlate with fewer hospitalizations and deaths.