If you are being treated with Xolair, you can be vaccinated with the COVID-19 vaccination at any time, but the ACAAI (American College of Allergy, Asthma, and Immunology) recommends that the COVID-19 vaccine and Xolair not be given on the same day since, if a reaction or a side effect occurs, it may be challenging to work out which injection was to blame. The ACAAI suggests separating the COVID-19 vaccination and Xolair by at least 24 hours. There is no reason to stop Xolair until the patient completes the course of the COVID-19 vaccinations.