Exacerbations and new onset of immune-mediated inflammatory diseases, such as psoriasis and hidradenitis suppurativa, have been reported following COVID-19 vaccination. In patients with hidradenitis suppurativa, recent studies have shown that those who received mRNA vaccines were 3.5 times as likely to develop flares following vaccination compared to patients who received non-mRNA vaccines, indicating that mRNA COVID-19 vaccines are associated with hidradenitis suppurativa flares. Similar findings have been found in other studies evaluating the association between COVID-19 vaccines and other immune-mediated inflammatory diseases such as psoriasis, atopic dermatitis, lichen planus, and alopecia areata. However, further research is warranted in larger populations to validate these findings.

The COVID-19 pandemic has highlighted intricate associations between SARS-CoV-2 infection and autoimmune skin diseases (ASDs). This review examines the bidirectional relationship between COVID-19 and ASDs including hidradenitis suppurativa, psoriasis, atopic dermatitis, alopecia areata, autoimmune bullous diseases, cutaneous and systemic lupus erythematosus, systemic sclerosis, dermatomyositis, and lichen planus. Current evidence indicates that SARS-CoV-2 may precipitate or worsen ASDs via mechanisms such as molecular mimicry, dysregulated cytokine signaling, and enhanced Th1/Th17 immune responses, leading to loss of self-tolerance and autoantibody production. Epidemiological studies have identified increased incidence and flares of psoriasis, hidradenitis suppurativa, and other ASDs following both COVID-19 infection and vaccination, with mRNA vaccines associated with a higher risk of flare in hidradenitis suppurativa compared with non-mRNA vaccines. Notably, severe COVID-19 is associated with a greater risk of new-onset autoimmune disease, and patients with pre-existing inflammatory skin conditions may have increased susceptibility to SARS-CoV-2 infection but experience less severe COVID-19 courses. These findings underscore the need for ongoing surveillance and mechanistic studies to clarify the immunopathogenic links between SARS-CoV-2 and ASDs and inform management strategies for affected patients in the context of both infection and vaccination.

Background: COVID-19 disease has been associated with flares or new onsets of various autoinflammatory diseases such as psoriasis and atopic dermatitis. Our aim is to investigate the occurrence and risk factors of flares or new onsets of Hidradenitis Suppurativa (HS) following COVID-19 disease. Methods: A retrospective cohort study was performed including 310 patients with HS following COVID-19 disease. Data on the rate of HS flares, new lesions, time of flare onset, and flare duration were recorded. Demographics, clinical characteristics, and treatment parameters were compared between patients with and without HS flares. Results: HS flares developed in 69 (22.2%) patients, with 14 experiencing their first episode. The median period between COVID-19 and flare onset was 17 days, with a median flare duration of 14 days. For new HS onset, the median period was 9.5 days, and the median duration was 13 days. Biologic treatment was less common in patients with flares (7.2% vs. 23.2%, p = 0.003), and fewer patients with flares were vaccinated (81.1% vs. 99.1%, p < 0.001). Multivariable analysis showed lower risk for flares in those receiving biologics (aOR = 0.14, p = 0.002) and those who were vaccinated (aOR = 0.02, p < 0.001). Conclusions: COVID-19 may trigger HS flares and new onset, with biologic treatment and vaccination offering protection.