Delayed urticaria cases attributed to COVID-19 vaccination

Key takeaways:

• Six patients had pre-existing chronic spontaneous urticaria that got worse, and 14 developed novel delayed urticaria.
• Symptoms developed between 8 hours and 2 weeks after vaccination.

SAN ANTONIO — Twenty patients at University of Washington allergy clinics developed delayed urticaria caused by COVID-19 vaccination, according to data presented at the American Academy of Allergy, Asthma & Immunology Annual Meeting.

“We looked at what types of vaccinations people received, their treatments and responses, and the durations of their symptoms, among other things,” Stacey R. Chu, MD, an internist with SSM Health Saint Louis University Hospital, said during her presentation.

The retrospective chart review analyzed patients with urticaria who visited allergy clinics at the University of Washington between Dec. 14, 2020, and Dec. 14, 2021. The researchers determined 20 patients had urticaria attributed to COVID-19 vaccinations.

Six of these patients had pre-existing chronic spontaneous urticaria that got worse after vaccination. Also, 14 experienced novel development of delayed urticaria after vaccination.

These developments occurred between 8 hours and 2 weeks after vaccination with the first or second dose of the Pfizer or Moderna COVID-19 vaccines.

By vaccine and dose, three patients developed symptoms after the first Moderna dose, four after the second Moderna dose, six after the first Pfizer dose and six after the second Pfizer dose. One patient received both the Moderna and Pfizer vaccine.

The clinics treated patients with H1-antihistamines, H2-antihistamines, leukotriene inhibitors, oral steroids, omalizumab (Xolair; Genentech, Novartis), cyclosporine and acupuncture.

“In the Pfizer group, all patients were managed with antihistamines and did not require separate therapy,” Chu said. “But in the Moderna group, some patients did need omalizumab and cyclosporine to control symptoms.”

Specifically, 33% of the patients who had received the Pfizer vaccine received steroids before they were evaluated by the allergy clinic. The patients who had received the Moderna vaccine did not receive any steroids.

These results indicate why it is important for primary care providers to identify urticaria and refer patients to an allergist, the researchers said. Also, the researchers said that these differences between patients who did and did not receive steroids raise questions about the mechanism of delayed urticaria after COVID-19 vaccination.

“Patients overall had improvement within a year, often within 6 months, and some patients had complete resolution,” Chu said.

Some patients experienced improvements within 1 month. However, 65% of patients experienced urticaria for more than 6 weeks before symptoms improved. More than half of these patients experienced improvements within 6 months, and some had complete resolution.

Patients who did not experience complete resolution required treatment, typically antihistamines alone, to maintain manageable levels of symptoms.

The researchers do not recommend that patients who develop urticaria or who experience worse symptoms in pre-existing urticaria avoid further COVID-19 vaccinations.

All the patients who had received the Pfizer vaccine continued to receive additional vaccination, but more than half of the patients who had received the Moderna vaccine discontinued their vaccination program.

In particular, the patients who did not receive step-up therapy with omalizumab and cyclosporine all received additional vaccination, whereas patients with more severe cases chose to avoid subsequent vaccination.

These differences indicated that vaccine hesitancy is a barrier, the researchers said, although a better understanding of this condition and patient education may alleviate these concerns.

“We do have plans to dive in further with a follow-up review,” Chu said.

The researchers said they will analyze additional data they have gathered since the first review, looking for trends while comparing the review groups. These further analyses will incorporate patient reported data as well.

“We hope that with this larger number of patients, we will have more information that will elucidate some of these interesting findings from our first study,” Chu said.