Urticaria relapse after mRNA COVID‐19 vaccines in patients affected by chronic spontaneous urticaria and treated with antihistamines plus omalizumab: A single‐center experience

Urticaria is a disease characterized by wheals and/or angioedema. Chronic spontaneous urticaria (CSU) occurs for longer than 6 weeks and appears independently of any identifiable exogenous stimulus. During the vaccination campaign for Coronavirus disease 2019 (COVID‐19) pandemic, several cutaneous adverse events have been described, among which urticaria lasting less than 6 weeks (acute urticaria, AU). AU due to vaccines can be IgE or non‐IgE mediated; the former typically develop within 4 h of drug exposure, the latter occurs later and the mechanism is unclear. In this retrospective study we analyzed the frequency and clinical characteristics of urticaria occurring after COVID‐19 vaccine (post‐vaccination urticaria relapse) in adult CSU patients treated with antihistamine and omalizumab, and in clinical remission.