- Credibility:
WICKER PARK — Doctors and officials are clamoring for antibody tests that could show if someone has had coronavirus, and some tests are being sold to the public. But do they actually work?
There are unproven theories that people who had COVID-19 will be immune to it after they recover, and researchers are still determining if recovered patients could safely return to work or if their plasma could be used to treat others with coronavirus. Officials also hope to use the antibody tests to track how many people have been infected with coronavirus.
But the tests are not yet accurate enough, and it’s still not known whether people who recover from COVID-19 can get it again, officials have said.
Gov. JB Pritzker said Friday antibody tests are less of a priority for the state than widespread distribution of infection tests because it’s not yet certain they’re accurate enough to show who has had coronavirus.
“The fact is that verifying those [antibody] tests has been difficult for everybody, and we don’t want people to get false negatives or false positives that would lead people to believe they’re immune or they’re not immune mistakenly,” he said. “We’re not gonna plunge into that ourselves at the state level.”
Pritzker said he’s worried the tests have been promoted by others “in a way that errs on the side of irresponsible” since no one knows if the tests work or if those previously sick with COVID-19 will be immune to the virus going forward.
“What I won’t do is run full speed ahead with these tests until they’re proven because, among other things, we would be offering people a false sense of security,” Pritzker said.
While some doctors are offering the tests, Pritzker urged people to wait before trying to get one. He said Vice President Mike Pence told him and other governors “much of it is not yet proven.”
An antibody test produced by Abbott Laboratories, an Illinois-based diagnostics company, received FDA approval this month. A handful of other tests were temporarily approved by the FDA through an emergency use authorization.
The University of Illinois at Chicago’s Division of Infectious Diseases was able to purchase a limited number of Abbott’s test kits for research purposes. Chicago doctors can access them, too.
Illinois and Chicago officials have said they do want to use the tests in the future to determine how widespread COVID-19 has been here and who could possibly be immune.
But Dr. Allison Arwady, commissioner of the Chicago Department of Public Health, said earlier this month her primary focus is still tracking active COVID-19 infections.
“We are interested in, first and foremost, making sure we are able to test anybody who has symptoms,” she said. “We need to get to a point where we’re not having to turn people away.”
False negatives possible, doctor warns
Your body creates antibodies as a natural immune response to a new virus, whether it’s the common cold or COVID-19.
Within the first 10 days of infection, the body sends out a temporary round of antibodies called IgM to collect information on the new virus. The cells eventually make IgG antibodies to kill the virus.
It’s the IgG antibodies — not the IgM antibodies — that can possibly tell us if we’ve had COVID-19 and possibly help others via our plasma. They stick around for at least a year and should be forever remembered by the cells, which explains the immunity theory.
Dr. Richard Novak, head of Infectious Diseases at UIC, cautioned the public against paying for antibody tests that have not yet been approved by the FDA.
If someone receives an antibody test before their body has made IgG antibodies, the results may not be accurate. A bad test may simply not be sensitive enough to pick up the virus at all. Either of these scenarios would result in false negatives.
The tests may also be too sensitive and accidentally detect other coronaviruses, such as the common cold. This would result in false positive reads — something Illinois officials have said they’re wary of.
“It’s not yet confirmed that these tests are able to explicitly identify COVID-19 antibodies versus coronaviruses that cause things like the common cold,” Pritzker said. “The tests must definitively identify antibodies for COVID-19 and nothing else for them to be fully effective.”
Think you’ve found a valid test?
Ask your health care provider for the name of the manufacturer and the test’s date of FDA EUA approval. Then, verify that information by checking this list.
I survived COVID-19. Can my antibodies help others?
There is a theory donations of antibody-rich plasma can help COVID-19 patients fight the virus.
This treatment, known as “convalescent plasma,” has been around for more than 100 years, but its efficacy has not yet been proven, Novak said.
Researchers in China recently tested this treatment on a handful of patients. While the patients all recovered, the results of the study were meaningless without a “negative control” group, Novak said.
In other words, it’s impossible to know whether the plasma did save these patients — or whether they would have and could have fought the virus naturally, without the help of another human’s antibodies.
The FDA has not approved convalescent plasma as a treatment for COVID-19 because doctors are not allowed to experiment with plasma donations.
The Chicago Medical Society is collecting plasma donations from COVID-19 survivors. Think you can help? Learn more online.
What antibody tests mean for researchers
At UIC, Novak’s team is using the Abbott tests in a “double-blind, randomized placebo controlled study” to test the theory of convalescent plasma.
The study began in April with 10 patients. Half of the patients will receive antibody-rich plasma; the other half will not, Novak said. The Abbott tests will help researchers determine antibody counts in various donors’ plasma.
This research process is standard in the medical research community as it is the best way to find out if a treatment truly works, free of bias by either doctors or patients, Novak said.
Are antibodies used in vaccines?
Kind of.
Vaccines, however, are different from convalescent plasma in that they are an “active” immunity treatment, Novak said.
Vaccines stimulate your cells to create antibodies on your own so your cell memory will know how to fight the virus in the future.
Plasma convalescence, on the other hand, is a “passive” treatment because you’re using someone else’s immune response instead of your own to kill a virus, Novak said.
Not the same as antiviral treatments
Antiviral drugs do not contain antibodies.
UIC is participating in a pilot study to test the efficacy of the drug remdesivir against COVID-19. The drug was proven effective in the fight against ebola in 2014. The COVID-19 trial will end soon.
Results are expected in mid-May, Novak said. (Learn more about the study here.)
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