Study Finds Link Between COVID-19 and Autoimmunity

A population-based study conducted by researchers from the Republic of Korea found a significantly higher risk of developing autoimmune and autoinflammatory conditions, such as rheumatoid arthritis (RA), lupus, Crohn’s disease, and alopecia, among individuals who had COVID-19, with risks particularly elevated for those with severe cases, Delta variant infections and those who were unvaccinated.

Using the National Health Insurance Service database and the Korea Disease Control and Prevention Agency’s COVID-19 registry, researchers analyzed 6,912,427 participants. Of these, 3,145,388 participants had COVID-19, and 3,767,039 were controls, both with a minimum of 180 days of observation. The sample was balanced for demographic and health factors and had a mean age of 53.39 years, and 46.4 percent of the participants were female.

COVID-19 was confirmed via polymerase chain reaction testing or physician-confirmed rapid antigen testing. Outcomes were measured by tracking autoimmune disease diagnoses (requiring at least three medical visits) and assessed using codes from the International Classification of Disease tenth revision (ICD-10). Inverse probability of treatment weighting (IPTW) was used to balance the cohorts by demographic, socioeconomic, lifestyle and comorbidity data.

Results showed patients with COVID-19 had an increased risk for a range of autoimmune diseases, including alopecia areata (adjusted harard ratio [AHR], 1.11), vitiligo (AHR, 1.11), Behçet disease (AHR, 1.45), Crohn’s disease (AHR, 1.35), rheumatoid arthritis (RA) (AHR, 1.09), alopecia totalis (AHR, 1.24), ulcerative colitis (AHR, 1.15), Sjögren syndrome (AHR, 1.13), systemic lupus erythematosus (SLE) (AHR, 1.14), ankylosing spondylitis (AHR, 1.11) and bullous pemphigoid (AHR, 1.62).

Men with COVID-19 were more prone to developing alopecia areata, vitiligo and RA, while women had heightened risks of alopecia totalis, Behçet disease, and bullous pemphigoid. Age-based analyses showed that participants under 40 years had higher risks of autoimmune conditions such as primary cicatricial alopecia and ulcerative colitis, while those over 40 exhibited risks for conditions such as Sjögren syndrome, SLE and ankylosing spondylitis.

The severity of COVID-19 was found to influence autoimmune risks, with patients in intensive care having markedly higher risks for sarcoidosis, Sjögren syndrome and bullous pemphigoid. The Delta-dominant period posed higher risks for autoimmune diseases than the Omicron period. Vaccination appeared to mitigate the autoimmune risks, with unvaccinated patients showing greater susceptibility to conditions like RA, SLE and Crohn’s disease. Sensitivity analyses with historical controls (prepandemic) confirmed similar trends, indicating the robustness of the results.