Catching COVID may increase chances of developing an autoimmune disease, study says

By Julia Marnin

A coronavirus infection may make it more likely for someone without an autoimmune disease to develop at least one in the months after the infection subsides, new research suggests.

Viral infections are known for the potential to lead to autoimmune diseases, when the immune system launches an attack against the body.

Now, the large study, published as a preprint on the server medRxiv in late January, specifically pinpoints the likelihood of autoimmune disease risks linked to COVID-19. The preprint, which has yet to undergo peer review, examined 40 autoimmune outcomes, representing 30 different diseases.

It may be about 43% more likely that someone without an autoimmune disease will develop one of the 30 autoimmune diseases after a COVID-19 infection, the study based in Germany found.

For those already living with an autoimmune disease, such as Crohn’s disease, rheumatoid arthritis and multiple sclerosis, there’s a smaller, but still heightened chance of developing an additional autoimmune disease after catching COVID-19, according to the research. The risk was found to be 23% more likely than those who don’t catch COVID-19.

The researchers consider their work the largest cohort study examining the link between COVID-19 infection and autoimmune diseases to date.

Health records of 614,407 people who caught COVID-19, confirmed by a PCR test, in the early pandemic through Dec. 31, 2020 were examined and compared with over 1.5 million people who didn’t catch the virus. Then, these individuals were followed up with until June 30, 2021.

The most common autoimmune diseases patients in the study developed

Among those who had gotten COVID-19, 6,489 people without an autoimmune disease developed one within three to 15 months after their infection, the study found.

The period after a COVID-19 infection is the post-acute period and is also commonly referred to as long COVID. The study defined the post-acute phase as three months after being diagnosed with COVID-19, which is in line with the World Health Organization’s definition. The Centers for Disease Control and Prevention defines post-COVID conditions as health problems that emerge at least four weeks after an infection.

Meanwhile, for those in the study who already had an autoimmune disease and got COVID-19, 1,744 developed a new one after their infections.

The risk for autoimmune diseases was higher if a preceding COVID-19 infection was considered severe, study authors noted.

The most common autoimmune diseases study participants developed after the virus were related to vasculitis, when blood vessels become inflamed, according to the research.

When it came to generally common autoimmune diseases, the highest risks for developing one after COVID-19, according to the study, were:

• Rheumatoid arthritis

• Sjögren disease

• Graves’ disease

• Hashimoto thyroiditis

Other autoimmune diseases that developed in study participants, to a lesser extent, included psoriasis, diabetes type 1, ulcerative colitis, multiple sclerosis, celiac disease, alopecia, vitiligo and more, the research shows.

The study’s findings fall in line with prior evidence about how viral infections are associated with developing autoimmune diseases, according to the researchers.

The research’s large study sample of hundreds of thousands of health records, and the follow-up period of three to 15 months, was noted as a major strength of the work.

“The impact of this study is huge — it’s the strongest evidence so far answering this question of COVID-19 and autoimmune disease risk,” Anuradhaa Subramanian, a research fellow of health informatics at the University of Birmingham in England, told Live Science. She wasn’t involved in the study.

The authors emphasized that since the study is observational, it doesn’t show a direct cause between a COVID-19 infection and the risk of autoimmune diseases.