Background: New onsets of chronic urticaria (CU) have been reported after repeated immunizations, mainly with the Moderna mRNA-1273 vaccine (Spikevax). This study aims to evaluate patients with CU after COVID-19 mRNA vaccination. The contribution of SARS-Cov2 infection, atopy and IgE against the vaccine was analyzed.
Methods: We monitored the features of patients who developed CU after vaccination through two surveys conducted in 2022 and 2023. Fifty individuals with CU underwent blood tests, and their results were compared with individuals without a history of urticaria (N = 135). The presence of anti-vaccine IgE was tested in 185 individuals with basophil activation tests (BAT). We assessed anti-SARS-Cov2 humoral response, and the presence of IgEs against common respiratory allergens (Phadiatop) as a surrogate for atopy
Results: Post-vaccination CU occurs after a median interval of 10 days and significantly more after the Spikevax booster, affecting middle-aged individuals (median 41, 66% females). In 2023, CU was still active in 53% of the cases. Inducible forms of CU, primarily dermographism, are reported in 54% (2022) and 61% (2023) of the cases. BAT positivity is not specific to CU, anti-nucleocapsid positivity, or atopy but is significantly associated with higher anti-spike neutralizing activities and younger age. Four CU patients tolerate an additional dose of mRNA vaccine with no disease exacerbation/recurrence.
Conclusions: The spikevax booster induces anti-vaccine IgE independently of CU, the latter being not directly associated with COVID-19 infection nor atopy. The tolerance to a new booster in 4/4 patients suggests that the Spikevax vaccine indirectly triggers CU in predisposed individuals.
Plain language summary : Urticaria is an itchy transient skin rash which can become in some cases recurrent and chronic. Repeated immunizations with COVID-19 mRNA vaccines can rarely lead to the development of chronic urticaria (CU), on average 10 days after vaccination. Here, we monitored people who developed CU after vaccination. One year following vaccination 53% of people still had CU. CU after vaccination was not directly associated with COVID infection, allergic predisposition or other effects of vaccination. Re-exposure to the vaccine was safe and well tolerated in four patients with vaccine-related CU suggesting an absence of a direct causality between the vaccine and CU. Therefore, managing CU post-vaccination should follow previously established guidelines as for other forms of CU.
