Introduction:
Cutaneous manifestations of acute coronavirus disease (COVID-19) have been well documented presentations, however, development of allergic skin manifestations after receiving COVID-19 booster vaccinations are rarely reported. Here, we present a case of a 24 year old otherwise healthy female who developed dermatographia within 2 weeks of receiving the third Moderna COVID-19 booster.

Case Summary:
A 24 year old healthy female presented for acute onset urticarial rash that developed upon direct skin contact. The rash demonstrated dermatographism when exposed to rubbing, scratching or intentional ‘writing’ along the skin. She had no other symptoms with presentation, but the rash was pruritic. Recent exposures included COVID 19 booster received 13 days prior to development of the rash. There was no personal history of new contact allergens including detergents or soaps, new medications, foods, occupational or environmental exposures. She had no prior history of anergic or chronic allergic pathologies nor reactions to previous vaccinations. Dermatological evaluation confirmed dermatographism and the patient was subsequently treated with second generation antihistamine therapy.

Discussion:
Dermatographism is an uncommon phenomenon seen in approximately 4-5% of the population (Bhute, et. al). Pathophysiology is linked to abnormal histamine response from immunologic and mechanical stimulation of mast cells, most closely resembling a type I hypersensitivity reaction. Most commonly, this reaction is seen in response to drug reactions and, in rare cases, dermal infections. The association between dermatographism and routine vaccinations have not been well demonstrated. In this case, the patient received the Moderna booster vaccination shortly prior to the development of symptoms. Although the Moderna booster dosage is half that of the primary vaccination series, it may lead to a heighted immunologic response in a certain subset of patients. Symptomatically, the condition can be well managed with antihistamine therapy, however, preventing the development of dermatographism with graded vaccination administration may be a prudent technique in patients with known predisposition to heightened allergic responses.

References and Resources

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