In a recent publication in the Journal of the American Academy of Dermatology, researchers conducted a nationwide, population-based study to explore the incidence and risk of autoimmune connective tissue disorders associated with mRNA-based COVID-19 vaccination.

The study participants included individuals who received at least one dose of the mRNA COVID-19 vaccination between September 8, 2020, and December 31, 2021. The researchers matched historical prepandemic controls for age and gender in a 1:1 ratio to compare the incidence rate and risk of disease outcomes between the vaccination and historical cohorts.

Of the 7,672,924 individuals who were vaccinated with at least one dose of the mRNA-based COVID-19 vaccine and had never been diagnosed with COVID-19, 3,838,120 were assigned to the vaccination cohort and 3,834,804 were assigned to the historical cohort.

The results revealed that participants in the vaccinated cohort versus historical cohort did not demonstrate any significantly augmented risk of alopecia areata (adjusted hazard ratio [aHR] = 0.98; 95% CI, 0.92-1.05); alopecia totalis (aHR = 0.89; 95% CI, 0.69-1.14); primary cicatricial alopecia (aHR, 0.91; 95% CI, 0.70-1.20); psoriasis (aHR = 0.89; 95% CI, 0.81-0.97); vitiligo (aHR = 0.96; 95% CI, 0.84-1.11); ulcerative colitis (aHR = 0.88; 95% CI, 0.72-1.07); rheumatoid arthritis (aHR = 0.92; 95% CI 0.87-0.98); systemic sclerosis (aHR = 0.82; 95% CI, 0.46-1.45);  and Sjogren syndrome (aHR = 0.90; 95% CI, 0.74-1.1) in addition to other autoimmune and autoinflammatory diseases. The authors also noted that the risk was comparable according to age, gender, type of mRNA-based vaccine, and cross-vaccination status.

Moreover, the researchers found a considerably augmented risk of myocarditis (aHR = 76.48; 95% CI, 18.67-313.39), pericarditis (aHR = 6.24; 95% CI, 3.8-10.24), and thrombocytopenia (aHR = 1.45; 95% CI, 1.31-1.61) in the vaccination cohort compared with the historical cohort.

Among females in the vaccinated group, there was an augmented risk of antineutrophil cytoplasmic antibody (ANCA)–associated vasculitis, although the number of events was very small (aHR = 5.09; 95% CI, 1.09-23.68). The researchers added that this finding "requires careful interpretation" since the number of events was minimal.

The authors wrote, "This nationwide study found that most autoimmune connective tissue diseases were not significantly increased after mRNA-based COVID-19 vaccination. However, limited statistical power prevented detection of potential risks for some rare outcomes. Nevertheless, results suggest any existing risk is not large. These findings could aid in the evaluation and management of autoimmune manifestations following vaccination for COVID-19."

Based on their findings, the authors concluded, "These findings suggest that most autoimmune connective tissue disorders are not associated with a significant increase in risk. However, caution is necessary when interpreting results for rare outcomes due to limited statistical power."

The authors also wrote, "Our data should relieve excessive public concern about vaccinations and not discourage clinicians from prescribing COVID-19 vaccines; however, long-term follow-up is necessary."

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