Rationale
COVID-19 mass vaccination efforts were implemented December 2020 and soon after vaccine hypersensitivity reactions were reported. Evidence-based information about side effects combats vaccine hesitancy. To improve our understanding of allergic side effects following mRNA COVID-19 vaccination, we characterized cases of urticaria and/or angioedema (U/AE) events secondary to COVID-19 vaccines.
Methods
U/AE events were abstracted from the COVID-19 Vaccine Allergy Case Registry (allergyresearch.massgeneral.org). Patient and reaction characteristics were summarized for events from February 13, 2021 to October 22, 2021.
Results
Of 455 unique patients from 44 US states, 58 patients (13%; mean age 49yrs [range:13-85yrs], 84% female, 76% White, 7% Black, 9% Asian, 9% Hispanic/Latino) experienced U/AE following vaccination. Most U/AE occurred after the first dose (n=43, 74%) from Pfizer-BioNTech and Moderna equally (n=29, 50%). Timing of U/AE onset was <4hrs (n=20;35%), >4hrs but ≤24hrs (n=11; 19%), and >24hrs (n=27; 47%). Ten (17%) patients had a history of chronic U/AE while 23 (40%) had other atopic comorbidities. Treatment included antihistamines (n=39; 67%); 3 (5%) received epinephrine and 18 (31%) received oral corticosteroids. Reaction treatment location was largely at home (n=15; 26%) or in the Emergency Department (n=14;24%), but 2 (3%) required hospitalization.
Conclusions
U/AE events comprised 13% of clinician reported COVID-19 vaccine allergy cases following mRNA vaccinations in this national case registry. The majority of cases occurred in those without underlying chronic U/AE; most cases had onset after 4 hours and were mild. Given timing of onset and benign course, many U/AE events after COVID-19 vaccination should not contraindicate future doses.
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