Dear Editor,

We read the article by Badier et al. entitled “IgA vasculitis in adult patients following vaccination by ChadOx1 nCoV-19”, published in Autoimmunity Reviews with interest. (1) We share the author’s view that the COVID-19 vaccine could be the trigger of IgA vasculitis in the reported case. At our secondary/tertiary rheumatology centre, we have been meticulously recording and following patients with systemic vasculitis for a more than a decade, and we recently reported 8 cases of systemic vasculitis temporally related to COVID-19 immunization. (2) Vasculitis in our cohort followed 7 to 20 days after vaccination. Remarkably, in our experience, not only small vessel vasculitis, but also cases of large vessel vasculitis were documented, the latter being as frequent as the former. Lately, we also treated another patient presenting 3 weeks after receiving the Pfizer-BioNTech vaccine with histologically proven skin limited IgA vasculitis that rapidly remitted after a short systemic glucocorticoid therapy.

Furthermore, we have been tracking cases of other autoimmune/autoinflammatory events developing in close association to vaccination against COVID-19. By 31 August 2021, 361,495 people in our region received at least one dose of the four different COVID-19 vaccines available in Slovenia (Pfizer-BioNTech and Moderna, Oxford/AstraZeneca and Jannsen/Johnson&Johnson). (3) During the same observation period, we documented 19 additional autoimmune/autoinflammatory events temporally related with COVID-19 vaccination (Table 1 ). Rheumatic polymyalgia was the most frequent manifestation followed by skin panniculitis and neuromuscular disorders. Interestingly, in 2 patients with adult-onset Still’s disease like picture, an additional potential trigger was documented: the first patient received immunization against tick-born encephalitis 14 days prior to receiving the COVID-19 vaccine, and the second patient had concomitant Epstein Barr virus infection. Furthermore, 2 patients recovered from COVID-19 infection 6 months prior to vaccination, and 3/19 patients had a history of a long standing rheumatic disease that was well controlled at the time of vaccination. Autoimmune/autoinflammatory events developed with an average delay of 17 days after either partial (i.e. first dose) or full vaccination in 7 and in 12 cases, respectively. The majority of patients were treated with a systemic glucocorticoid, while 1 patient with focal necrotizing panniculitis needed surgical therapy.

Table 1

Vaccination may induce de novo autoimmune diseases, particularly in genetically predisposed individuals. (4) Reports of vasculitis (most commonly cutaneous vasculitis and IgA vasculitis) following vaccination (most frequently the influenza vaccine) have been documented. (5,6)

Regarding pathogenic mechanisms, molecular mimicry, hyperactivation/bystander activation of the immune system, loss of immune tolerance, neoantigen formation and antibody triggering have all been hypothesized. Though the pathogenic mechanisms of COVID-19-associated vasculitis have not been elucidated yet, these mechanisms might also play a role in COVID-19 vaccine-associated vasculitis or other autoimmune phenomena.

In conclusion, our experience shows that COVID-19 vaccines should be considered as a risk factor for inducing not only vasculitis but also other systemic autoimmune and autoinflammatory phenomena, and that the relationship between vaccination and autoimmunity should be further investigated.

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