Should you get a coronavirus antibody test? Here’s what health experts say.
If you or someone you know had a weird cold earlier in the year, you might wonder if it could have been coronavirus.
As COVID-19 cases spike again the United States after a few months of Americans staying at home, it’s tempting to wonder if you might be immune. Antibody tests, or serological tests, that detect the presence of certain proteins in the blood could show if you might have already had the virus.
But not all tests are reliable, and public health experts aren’t sure exactly how you can act on results. Rather than guaranteeing your safety, the they could lend a dangerously false sense of security.
It’s not clear how long antibodies protect you against catching COVID-19 again, or to what extent you can be exposed to the virus before catching it, said Dr. Bruce Hall, vice president and chief quality officer for BJC HealthCare in St. Louis.
“Let’s say your result is positive (for antibodies). What does that really mean? It means at some point you were exposed to the virus enough that your body generated a response,” Hall said. “That’s interesting, but that does not mean that it’s safe for you to ignore precautions or to assume that you can never catch this disease again.”
Still, antibody testing is an important public health tool for studying the prevalence of the virus and for determining how widespread it was in the United States before officials started tracking it closely. A study released last week by the U.S. Centers for Disease Control showed that COVID-19 infections were 10 times higher than originally believed.
Experts hope to strike a balance where antibody testing serves its public health purpose in tracking the virus, but can also be used on a personal level to inform decisions about your behavior during a pandemic.
Should you get an antibody test for COVID-19?
Until more is known about serological tests, health professionals say you won’t be able to change your behavior based on results, either positive or negative.
This is in part because the tests aren’t 100% reliable. Though they’ve vastly improved in recent months, even tests approved by the U.S. Food and Drug Administration can produce either a false negative or a false positive.
“If the test is negative, you’ve never been exposed or not enough to generate antibodies. If you get that result, nothing about your life changes,” Hall said. “Let’s say you get a positive result and pretend we know there was no mistake. Again, the answer is no. If you have a positive result, there’s some chance you could get infected again and you still need to use all the precautions.”
In either case, public health experts still recommend frequent hand washing, social distancing and wearing a mask.
For now, the value in getting tested is if you’re interested in contributing to research on immunity or a vaccine. If you know you had COVID-19 and recovered, you might be able to help.
The tests also produce large amounts of nationwide serology data to show whether the disease is growing or fading. The Red Cross offers a free FDA-approved antibody test in certain areas for anyone who donates blood. The Red Cross shares anonymous data from test results with the CDC.
“It will give our donors more insight into their exposure and it will also help with public health overall looking for information where people have come in contact with COVID-19,” said Sharon Watson, a spokeswoman for the Red Cross of Missouri and Arkansas.
If you do get an antibody test, you should consult with your doctor or a local public health official about the results, Watson said. You should also ensure the FDA approved the test, and you probably shouldn’t pay for one either, Hall said. A full list of approved tests is available on the FDA’s website.
But the U.S. is still “months away, if not longer” from fully understanding coronavirus antibodies, Hall said.
“Today, we’re really worried that (antibody testing) will create some unintended consequences.”
When will coronavirus antibody tests be more useful?
Eventually, scientists will know enough about COVID-19 immunity to be able to say that a certain level of antibodies will protect you for a certain amount of time. That could help you understand if it’s safe to go back to work or school, and for how long.
But until scientists fill the knowledge gap about how much antibodies will protect you, serological tests will only be useful in clinical and research settings, not for personal use.
Researchers nationwide have been busy conducting large, diverse studies on serological tests, including 300 scientists and clinicians who participated in a U.S. Department of Health and Human services workshop in May.
The researchers discussed the status of antibody testing in the U.S. and how the tests can be used, said Cristina Cassetti, deputy director of the microbiology and infectious disease division at the National Institute of Allergy and Infectious Diseases.
Scientists do what they can to accelerate those studies, such as recruiting groups who are at higher risk of catching the disease or transmitting it, according to Cassetti. Health care workers in an urban area, for example, might catch the disease, recover and show the presence of antibodies quicker than the average person.
Studying this population might allow scientists to gather data quicker, and possibly produce recommendations an individual could use sooner.
Apart from accelerating studies, scientists hope to develop a centralized database of antibody information public health officials can use to make local decisions about reopening.
The National Institutes of Health and the CDC have partnered to develop “something like a dashboard” that would allow officials to see data about how many people have coronavirus antibodies at any given time in a city or county, Cassetti said. It could also help them compare information about past infections to study how many people have been exposed to COVID-19.
“It would be a very useful tool to have to help both for public health officials to make decisions as well as a good tool to plan for clinical trials,” Cassetti said.
But for the time being, unless a person wants to be part of research on a vaccine or antibodies, getting a serological test for personal use won’t be very helpful.
“We just have to sit tight as much as possible and hopefully in the next few months we can get enough data that will be more useful at the personal level,” Cassetti said. “It’s amazing how much progress we’ve made in the last few months, but of course these studies take awhile.”
This story was originally published July 2, 2020 at 5:00 AM.
