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COVID-19 Vaccination Well-tolerated in Patients with Mast Cell Activation Syndrome

AAAAI News Release

April Presnell
AAAAI Executive Office: (414) 272-6071

February 1, 2022

Study presented at the 2022 AAAAI Annual Meeting also suggests vaccine hesitancy is higher among this group of patients than the general public, despite tolerability of vaccination.

Milwaukee, WI – Patients with suspected or confirmed mast cell activation syndrome (MCAS) can tolerate COVID-19 vaccination, according to an abstract being presented at the 2022 Annual Meeting of the American Academy of Allergy, Asthma & Immunology (AAAAI).

MCAS is a medical condition that causes mast cells to release too many chemicals into the patient’s body, causing repeated episodes of anaphylaxis symptoms such as hives, swelling, low blood pressure, difficulty breathing and severe diarrhea.

The retrospective study analyzed 300 patients from a single academic center who had confirmed or suspected MCAS between December 2020 and November 2021. Researchers found that 105 of the 300 patients in the study received at least one COVID-19 vaccine dose. Of those who received at least one dose, side effects were similar as those described by the U.S. Centers for Disease Control and Prevention, including pain, redness, and swelling at the injection site, fever, chills, fatigue, headache, muscle pain and nausea.

Some patients in the study described neurologic symptoms as well. These included orthostatic intolerance, neuropathic pain and dysautonomia. Few patients included in the study reported the immediate onset of symptoms associated with mast cell mediator release including flushing, urticaria, diarrhea or anaphylaxis. In most cases, side effects resolved within 21 days.

“What this shows us is that both replication-incompetent adenovirus and mRNA vaccines for COVID-19 can be tolerated in patients with suspected or confirmed MCAS,” said primary author Jessica D. Macdougall. “Despite this, only 35% of these patients are fully vaccinated against COVID-19 compared to 58.4% of the general U.S. population. It’s important we share this with patients to make them aware that it is possible to safely be vaccinated, as long as a discussion of the risks and benefits is had with their healthcare provider.”

Visit to learn more about COVID-19 and MCAS. Research presented at the AAAAI Annual Meeting, February 25-28 in Phoenix, Arizona, is published in an online supplement to The Journal of Allergy and Clinical Immunology.

The American Academy of Allergy, Asthma & Immunology (AAAAI) is the leading membership organization of more than 7,100 allergists, asthma specialists, clinical immunologists, allied health professionals and others with a special interest in the research and treatment of allergic and immunologic diseases. The AAAAI is the go-to resource for patients living with allergies, asthma and immune deficiency disorders. Established in 1943, the AAAAI has more than 7,100 members in the United States, Canada and 72 other countries. The AAAAI’s Find an Allergist/Immunologist service is a trusted resource to help you find a specialist close to home.