LAUSR

Patients who developed an immediate allergic reaction within the first 4 hours of COVID-19 vaccine injection are recommended not to receive the same vaccine again. This recommendation mainly focuses on the mRNA and adenoviral vector COVID-19 vaccines, but data for whole virus vaccines are unknown. We report seven patients who developed an immediate reaction within 4 hours (6 generalised urticaria, 1 localised urticaria) after the first vaccination with CoronaVac, the inactivated SARS-CoV-2 vaccine. The results of skin tests and basophil activation tests suggest that spike peptides play a role in exacerbating urticaria in some patients. However, all subjects who developed urticaria within 4 hours after CoronaVac vaccination could be successfully revaccinated without graded challenge, although recurrent urticaria was common. This preliminary result showed that acute urticaria alone should not be contraindicated for the second dose of CoronaVac if the supply of alternative vaccines is limited.