New-onset and recurrence of psoriasis following COVID-19 vaccination: a nationwide cohort study in Korea

Background: While the acute global phase of the COVID-19 pandemic has subsided, the potential association between COVID-19 vaccination and immune-mediated diseases, including psoriasis, remains of clinical and scientific interest.Objective: To investigate the association between COVID-19 vaccination and new-onset (Study 1) or recurrent (Study 2) psoriasis.Methods: Using the National Health Insurance Service claims database in South Korea, we analyzed individuals who received COVID-19 vaccines between February 26 and July 31, 2021.In Study 1, the incidence of new-onset psoriasis in vaccinated individuals was compared with matched unvaccinated controls.In Study 2, psoriasis recurrence was evaluated among patients with a prior diagnosis who had remained untreated for the preceding four years.Propensity score matching (1:1) was performed, and each participant was followed for five months.Adjusted hazard ratios (aHRs) were calculated using a multivariate Cox proportional hazards model.Results: Study 1 included 673,048 vaccinated individuals and matched controls.Vaccination was associated with a higher risk of newonset psoriasis (aHR 1.36, 95% CI: 1.23~1.51).Study 2 included 4,211 vaccinated and matched unvaccinated patients with prior psoriasis; vaccination was associated with an increased risk of recurrence (aHR 1.83, 95% CI: 1.15~2.93).Sensitivity analyses excluding COVID-19 infection yielded consistent results.Increased risks of new-onset psoriasis were observed across all vaccine platforms, while recurrence was significantly associated with mRNA and mixed vaccines.In both studies, the majority of cases were managed with topical corticosteroids, with similar treatment patterns between vaccinated and unvaccinated groups. Conclusion:This study demonstrated a significantly increased risk of new-onset or recurrent psoriasis following COVID-19 vaccination in South Korea.However, rather than avoiding vaccination indiscriminately, decisions should be made by carefully weighing potential risks and benefits.In the context of emerging infectious diseases, clinicians should remain attentive to the possible effects of vaccinations on immune-mediated skin disorders while supporting balanced, individualized patient care.