A recent study published in eClinicalMedicine reports that the coronavirus disease 2019 (COVID-19) can increase the risk of various autoimmune diseases; however, this risk appears to be mitigated by vaccination against COVID-19.
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The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is the virus responsible for the coronavirus disease 2019 (COVID-19), has caused over 768 million infections and 6.9 million deaths worldwide. Previous studies have reported that a diagnosis of COVID-19 increases the risk of new-onset autoimmune diseases that affect the nervous system, musculoskeletal system, and endocrine system.
Many autoantibodies, including those targeting cyclic citrullinated peptide (CCP) the nucleus, have been detected in COVID-19 patients. These autoantibodies are known biomarkers for several autoimmune diseases, including psoriasis, inflammatory arthritis, Grave's disease, and Guillain-Barré syndrome (GBS).
During SARS-CoV-2 infection, an aberrant production of pro-inflammatory cytokines, especially interleukins (ILs) and tumor necrosis factor-a (TNF-a), often occurs. These cytokines disrupt the innate and acquired immune responses, thereby leading to the induction of autoimmunity. Likewise, virus-induced cytokines can also increase the risk of autoimmune responses by activating self-reactive T-cells without antigen recognition.
COVID-19 increases risk of autoimmunity
The current observational retrospective cohort study was conducted between April 2020 and November 2022. Herein, researchers analyzed electronic health records of Hong Kong residents, COVID-19 testing results, and COVID-19 vaccination data, all of which were obtained from concerned health authorities.
Based on COVID-19 testing results, the study population was categorized into COVID-19 and non-COVID-19 groups. Appropriate statistical analyses were performed to estimate the risk of new-onset autoimmune diseases following COVID-19. Moreover, COVID-19 vaccinated participants were compared with unvaccinated participants to assess the protective efficacy of COVID-19 vaccines against autoimmune diseases.
A total of 1,028,721 COVID-19 and 3,168,467 non-COVID-19 individuals were identified from the dataset. The most prevalent comorbidities in the study population included diabetes, cerebrovascular disease, and malignancy.
A higher incidence rate of autoimmune diseases was observed in the COVID-19 group as compared to that in the non-COVID group. The median duration between COVID-19 diagnosis and new-onset autoimmune disease varied from 41 to 246 days.
COVID-19 patients were associated with an increased risk of developing pernicious anemia, spondyloarthritis, rheumatoid arthritis and other autoimmune arthritis, psoriasis, pemphigoid, Graves' disease, anti-phospholipid antibody syndrome, immune mediated thrombocytopenia, multiple sclerosis, and vasculitis as compared to those without a history of COVID-19.
Overall, the impact of COVID-19 on autoimmune disease risk remained the same across gender. However, a significantly higher risk of spondyloarthritis and Graves' disease was observed in male and female participants, respectively.
The highest risk of COVID-related autoimmune arthritis, pemphigoid, and anti-phospholipid antibody syndrome was observed among older adults 65 years and older. Similarly, the highest risk of spondyloarthritis, rheumatoid arthritis, psoriasis, and multiple sclerosis was observed in individuals between 41-64 years of age. Moreover, an increased risk of Graves' disease was observed in those between 18-40 years of age.
Among severe COVID-19 patients who required hospitalization, a higher risk of transverse myelitis and inflammatory bowel diseases (IBDs) was observed. However, non-hospitalized patients did not exhibit a similar increased risk of these condition.
Regarding COVID-19 vaccination, a lower risk of developing autoimmune arthritis, pemphigoid, immune-mediated thrombocytopenia, Graves' disease, anti-phospholipid antibody syndrome, and systemic lupus erythematosus was observed among vaccinated patients as compared to unvaccinated individuals.
Considering the site of infection, an increased trend was observed in organ-specific autoimmune disease and systemic autoimmune disease.
Some studies have reported newly diagnosed autoimmune disorders such as autoimmune liver diseases, GBS, and immunoglobulin A (IgA) as potentially rare side effects of COVID-19 vaccination. Importantly, the current study findings confirm the general consensus that COVID-19 vaccination is safe and does not increase the risk of incident autoimmune disorders among vaccinated individuals within 28 days of receiving the second vaccine dose.
SARS-CoV-2 infection was found to increase the risk of developing a wide range of autoimmune diseases; however, this risk can be reduced by two doses of COVID-19 messenger ribonucleic acid (mRNA) vaccines.
Given these findings, scientists advise physicians to consider examining the autoimmunity status in COVID-19 patients for an early diagnosis and better management of new-onset autoimmune diseases. Moreover, the study findings can be presented in public awareness campaigns to encourage vaccine uptake.