Setting: Out-Patient Primary Care Office.
Patient: A 74-year-old female with no past medical history of allergies presented to her primary care doctor 8 days post-injection of COVID-19 vaccine with a delayed-type hypersensitivity reaction. The patient received her second dose of 0.5 mL intramuscular injection of Moderna’s mRNA COVID-19 vaccine on February 19, 2021. Her first dose of the mRNA vaccine was administered 30 days prior to this dose and caused no adverse drug reactions. On day 8, post-injection of her second dose of the vaccine, the patient presented with a circular, erythematous, pruritic, and raised rash measuring 6 inches in diameter surrounding the injection site. The patient reported that the area was painful to light touch. The rash persisted for 5 days.
The patient was instructed to apply ice daily, increase daily fluid intake, and do gentle stretching exercises when her rash was present. She received no empiric antibiotic therapy but was counseled to contact her primary care physician if any signs of infection developed. At follow-up 3 weeks post-injection, the patient’s rash had completely resolved and there were no long-lasting side effects to the second dose of the COVID-19 vaccine.
There have been other rare reports of a similar hypersensitivity reaction to the COVID-19 vaccination. However, this is the first reported case, to our knowledge, where the rash persisted for 5 days as seen in this case. It is important for all general practitioners to educate their patients prior to receiving the Moderna vaccine of this rare but potential side effect. It is equally imperative for practitioners to reassure patients that this side effect does not warrant any special treatment, nor is it considered a contraindication from receiving either dose of the novel COVID-19 vaccine.
Delayed-type hypersensitivity skin reactions to the COVID-19 vaccine are uncommon but have been reported in a small minority of patients receiving the new vaccine. Previously we had reports of these hypersensitivity reactions resolving within 24–48 h, but as this case demonstrates, it is possible for patients to experience a longer manifestation but with a similar resolution. Despite the prolonged course of this particular rash the patient did not experience any long-term or serious adverse effects to the COVID-19 vaccine and should not dissuade future patients from receiving the vaccine.
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