LAUSR

urrently, the treatment of Chronic Urticaria (CU) follows n international consensus. When CU does not respond to ntihistamines for up to 4 weeks, the use of omalizumab is ecommended for at least 6 months, at a dose of 300 mg ubcutaneously every four weeks.1,2 There is a formal contraindication for vaccination with n attenuated live virus in patients using immunobiological gents. As of July 2017, in Brazil, there was an epidemic of Yellow ever (YF) disease and the World Health Organization (WHO) ecommended immunization with the Yellow Fever Vaccine YFV) using the fractionated dose, on a temporary basis as strategy to prevent the disease.3--5 As omalizumab acts exclusively on mast cell and basophil gE and does not affect cell immunity, the study group recmmended vaccination for YF in patients from areas at risk or the disease.6 The present study aimed to evaluate the occurrence f adverse reactions to YFV in patients with CU with and ithout the use of omalizumab and/or antihistamines. As secondary objective, the reason for the non-vaccination f some patients using omalizumab was evaluated. A ross-sectional and observational study was conducted, by ollecting demographic data from 89 patients who were eing followed at the Urticaria Outpatient Clinic between anuary and April 2019.