I have similar urticaria develop 15 days after booster taken on Dec 12. My first 2 shots were Moderna and booster was Pfizer. It has been 2 months and urticaria persists. I have been on Zyrtec everyday and 3 weeks ago added Pepcid. Urticaria still persists. I want to know if there is any case where symptoms of urticaria ever resolved? How long did it take and seems to help?