New findings from Yonsei University researchers in South Korea suggest that contracting COVID-19 could raise the chance of developing autoimmune conditions such as Crohn’s disease, hair loss conditions, and sarcoidosis. The study appeared in JAMA Network Open, a peer reviewed medical journal.
The team examined data from roughly 355 thousand individuals who had COVID-19 and compared them with more than six million people who did not contract the virus. The comparison aimed to uncover any shifts in autoimmune risk linked to infection over a large population sample.
Among those diagnosed with COVID-19, the likelihood of experiencing various forms of alopecia areata, a condition that can cause patchy hair loss and sometimes bald patches, rose by 12 to 74 percent. The risk of vasculitis, an inflammatory condition affecting blood vessels, also showed notable increases ranging up to 74 percent in some cases. In several instances, the risk of developing autoimmune conditions tripled, and overall autoimmune risk rose by about 68 percent. Specifically, the incidence of Crohn’s disease and sarcoidosis—both autoimmune disorders characterized by intestinal inflammation and granuloma formation in multiple organs, respectively—grew by around 59 percent. All of these conditions arise from immune system activity turning against the body itself, creating autoimmune responses in susceptible individuals.
The researchers propose that the heightened autoimmune risk after a COVID-19 infection may be linked to the body’s interferon response. Interferons are inflammatory signals that help fight viral infections, but they can also trigger the production of autoantibodies. When autoantibodies attack healthy tissues, this can manifest as autoimmune disease, especially in people with a preexisting predisposition.
Overall, scientists emphasized that the risk of developing an autoimmune disease after a COVID-19 infection in any individual is still very low, with estimates suggesting fewer than 1 percent of those infected would go on to develop such a condition. They also noted that severe illness and limited vaccine access could heighten this risk in some populations, underscoring the role of vaccination as a preventive measure in reducing severe outcomes and potential autoimmune complications.
Earlier research in the field has noted that certain antibody types can neutralize a substantial portion of the diverse HIV variants. In that body of work, scientists identified special antibodies capable of neutralizing about a third of the approximately 200 viral variants tested, illustrating the broader importance of the immune system’s adaptive responses in protecting against evolving pathogens.