A new study has found that people who’ve had COVID-19 may be at higher risk for developing new autoimmune disorders than individuals who’ve never had this viral illness.
The research, published October 6 in JAMA Network Open, concluded that infection with the coronavirus increased the likelihood of developing a number of autoimmune disorders, including alopecia areata and alopecia totalis, marked by hair loss; ANCA-associated vasculitis, involving inflammation of the small blood vessels; the gut disorder Crohn’s disease; and sarcoidosis, characterized by nodules in the lungs or lymph nodes.
These findings support earlier research suggesting that the body’s immune response to COVID-19 plays a role in triggering certain autoimmune conditions, says the study’s first author, Sung Ha Lim, a researcher and physician in the department of dermatology at the Yonsei University Wonju College of Medicine in Seoul, South Korea.
Unvaccinated People Were at Higher Risk for Autoimmune Diseases
Notably, when analyzed by COVID-19 vaccination status, the unvaccinated people in the study were more susceptible to certain autoimmune diseases than the vaccinated people.
“People who are wondering if they should get a COVID vaccine should keep in mind that it can prevent them from getting other diseases they may not have even thought of,” says PJ Utz, MD, a researcher and professor of medicine in immunology and rheumatology at Stanford Medicine in California.
Study Included More Than 350,000 People With COVID-19
The Korean researchers identified more than 350,000 individuals diagnosed with COVID-19 via polymerase chain reaction (PCR) testing from October 8, 2020, to December 31, 2021.
Then the team compared the COVID-19 group to more than six million healthy people who had no evidence of COVID-19 infection.
A comparison of the data revealed that the instances of alopecia areata, alopecia totalis, antineutrophil cytoplasmic antibody (ANCA)–associated vasculitis, Crohn’s disease, and sarcoidosis were higher in the COVID-19 group.
The analysis revealed that patients who had COVID-19 illness severe enough to land them in a hospital were at greater risk for many more autoimmune conditions, including alopecia totalis, psoriasis, vitiligo, ANCA-associated vasculitis, Crohn’s disease, ulcerative colitis, rheumatoid arthritis, Sjögren’s disease, and ankylosing spondylitis.
Researchers Have Been Investigating Autoimmune Issues Since Early in the Pandemic
The study also advances earlier research linking COVID-19 to increased incidence of autoimmune diseases in general.
For instance, a study published in June 2023 in Clinical Rheumatology found that COVID-19 was associated with a 42.6 percent increased relative risk that a person would acquire an autoimmune disease such as rheumatoid arthritis, notes Dr. Utz. He is the coauthor of a study published in Nature Communication in 2021 that found new-onset autoantibodies in hospitalized patients with COVID-19. (He was not involved in the JAMA Network Open study.)
Autoantibodies can be thought of as “misguided” or disease-causing antibodies, Utz explains. Instead of responding appropriately to disease-causing antigens, they attack the body’s own proteins.
Autoantibodies Can Exist Years Before Autoimmune Disease Appears
Previous studies have shown that in autoimmune conditions such as type 1 diabetes, lupus, and rheumatoid arthritis, people develop autoantibodies months, years, or even a decade before they actually get the disease, so they’re in a kind of pre-autoimmune state, says Utz.
“And it’s long been hypothesized that viruses can be a trigger that would push them over the edge, such that they develop full-blown disease,” he says.
Because so many people have been infected with COVID-19, scientists now have an abundance of samples to analyze for associations between viral infections and autoimmune diseases. Utz calls the new study “additional evidence of how it does appear as if a virus can trigger new autoimmune diseases.”
More Multi-Ethnic Studies Are Needed
A weakness of the new study is that the subjects represent just one population: Almost everybody was of Korean descent.
This is important because different autoimmune conditions are more prevalent in different races. “For example, this study didn’t find an association with lupus [which other studies have found], but lupus is also less common in the Korean population,” Utz says.
Healthcare Providers Need to Be Vigilant
Given that the majority of people in the United States and around the world have had COVID-19, it’s really not practical to start screening everyone for all the different autoimmune conditions, says Utz.
“But I do think we need increased vigilance when patients come in to see their provider, just being on the lookout for symptoms and then being more aggressive about doing a workup if they do see things consistent with an autoimmune or inflammatory disease,” he says.