Differential Diagnosis
Several etiologies are considered, such as COVID vaccine-induced, mast cell defects, food-related allergies, autoimmune conditions, and infectious causes. Because the urticarial rash appeared shortly before her positive PCR test and she had accompanying moderate viral symptoms, the urticaria is thought to be a presenting sign of her COVID-19 infection. A detailed history was taken and did not reveal any concern for new exposure to food, use of over-the-counter medications, recent use of any kind of medications or herbal supplements, as well as no history of a similar attack; and it was unlikely to be an anaphylactic reaction as it was progressive worsening over 3 days duration, other suspected infection were excluded after screening and cultures. After being diagnosed with COVID-19, a trial of observation with antihistamines was felt.