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.