Features of chronic urticaria after COVID-19 mRNA vaccine over time

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.

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.

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.

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.