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.