Previous research indicates that patients with CU commonly express apprehension about disease exacerbations and fear of reactions following COVID-19 vaccinations, which may result in vaccine hesitancy.

In a recent study published in The Journal of Allergy and Clinical Immunology, researchers evaluated the frequency and risk factors for CU exacerbation and adverse reactions in CU patients after COVID-19 vaccinations.

The researchers conducted the Effects of COVID-19 Vaccination on Chronic Urticaria Patients (COVAC-CU) study, which is an international multicenter, observational study of Urticaria Centers of Reference and Excellence (UCAREs) that retrospectively assessed the effects of COVID-19-vaccination in CU patients aged ≥18 years and vaccinated with one or more doses of any COVID-19 vaccine. The researchers also evaluated CU exacerbations, severe allergic reactions, and other adverse events (AEs) associated with COVID-19 vaccinations and their correlation with various CU parameters.

The study population comprised 2,769 adults (average age, 43.7 years; 71.7% women) with CU treated at 50 member centers of the UCARE network in 26 countries between August 2021 and March 2022.

Of the 2,769 participants, 70.9% had chronic spontaneous urticaria (CSU), 12.2% had chronic inducible urticaria, and 16.9% had both. The researchers noted that 90% received at least two doses of a COVID-19 vaccine. The authors also pointed out that the majority of patients were receiving treatment for CU and had well-controlled disease.

The results revealed, “The rate of COVID-19 vaccination-induced CU exacerbation was 9%. Of 223 patients with CU exacerbation after the 1st dose, 53.4% had a recurrence of CU exacerbation after the 2nd dose. CU exacerbation most often started <48 hours after vaccination (59.2%), lasted for a few weeks or less (70%), and was treated mainly with antihistamines (70.3%).”

Findings indicated that the factors that augmented the risk for COVID-19 vaccination-induced CU exacerbation included female gender, disease duration shorter than 24 months, having chronic spontaneous versus inducible urticaria, usage of adenovirus viral vector vaccine, nonsteroidal anti-inflammatory drug/aspirin intolerance, and having concern about getting vaccinated, while being on omalizumab treatment and Latino/Hispanic ethnicity lowered the risk.

The results also indicated that percentages of patients reporting vaccine-related adverse effects included 43.5% (n = 1,124) after the first dose of a vaccine; 44.7% (n = 1,043) after the second dose; 45.4% (n = 283) after the third; and 33.3% (n = 9) after dose four.

The most common reactions reported were local reactions in 839 patients (30.3%), fever in 527 (19%), fatigue in 532 (19.2%), muscle pain in 511 (18.5%), joint pain in 203 (7.3%), and headache in 412 (14.9%).

Additionally, seven patients with CSU reported severe allergic reactions, four of which transpired within an hour of vaccination, and none of them received any adrenaline treatment. Also, four of these seven reported exacerbations.

Treatments for exacerbations involved second-generation antihistamines (70.2%) and systemic glucocorticosteroids (13.4%); however, 10% of patients did not obtain treatment for their exacerbations.

Based on their findings, the authors wrote, “In this study, even though more than half of CU patients had concerns about being vaccinated, only a minority (9%) experienced CU exacerbation after COVID-19 vaccination. Adverse reactions and CU exacerbation were rare despite the low rate of premedication before vaccination (~5%).”

The authors concluded that COVID-19 vaccination leads to disease exacerbation only in a small number of patients with CU and is generally well tolerated.

The authors wrote, “COVID-19 vaccination causes urticaria exacerbations in only a minority of chronic urticaria patients, systemic reactions are rare, and the frequency of common patient-reported adverse events is not higher than in clinical trials.”

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