Objective: Although the factors that trigger and exacerbate chronic spontaneous urticaria (CSU) are well known, there is still a lack of information about the effects of COVID-19 vaccines on CSU. This study aimed to investigate exacerbations/relapses triggered by COVID-19 vaccines in patients with CSU who are well controlled with treatment or in remission.

Materials and Methods: The study included 350 CSU patients. Demographic and clinical characteristics were collected from patients` medical records. The seven-day urticaria activity score (UAS7) and urticaria control test (UCT) were evaluated separately during the onset of the disease, pre-vaccination, and post-vaccination periods.

Results: The mean age was 39.89±13.30 years and 74.6% of the patients were female. A total of 227 patients were vaccinated with the Pfizer/BioNTech mRNA vaccine, 67 with the Sinovac/CoronaVac inactivated vaccine, and 54 with both vaccines. Urticaria exacerbations/ relapses were observed in a total of 76 patients, and most CSU exacerbations/relapses occurred after the first dose (n=46). Median UAS7 scores increased significantly in the post-vaccination period in patients who experienced urticaria exacerbation (p<0.0001). Median UCT scores were significantly decreased due to urticaria exacerbation with vaccination (p<0.0001).

Conclusion: Both mRNA and inactivated COVID-19 vaccine may lead to exacerbations or relapses in patients with CSU. Even so, exacerbations/relapses associated with COVID-19 vaccines can be easily controlled with treatments and do not preclude subsequent doses.