A case of severe cutaneous adverse reaction following administration of the Janssen Ad26.COV2.S COVID-19 vaccine

On 21 January 2021, an interim analysis of a phase-3 clinical trial revealed that the investigational, recombinant-vector COVID-19 vaccine developed by Janssen Pharmaceuticals, Janssen Ad26.COV2.S, was both effective and safe in preventing moderate and severe COVID-19 in adults.1 The vaccine was approved in late February 2021 by the Food and Drug Administration, following Pfizer's BNT162b2 and Moderna's messenger RNA-1273 approval in in December 2020. All 3 vaccines are considered safe by clinical trials. Fatigue, myalgias, and headaches have been reported in up to 10% of both of the Pfizer and Moderna vaccine recipients.2 About 1.5% of the patients who received the Moderna vaccine reported hypersensitivity reactions, such as rash and urticaria, and similar morbilliform hypersensitivity rashes have been reported with the Pfizer vaccine.3,4 Johnson and Johnson's vaccine had generally mild side effects in clinical trials, including fever in 9% of volunteers.1 As the number of vaccinated individuals in the general population rises, sporadic, atypical reactions are more likely to be observed and reported. Herein, we report a case of a 74-year old man who experienced a severe cutaneous adverse reaction (SCAR) following administration of the Janssen Ad26.COV2.S vaccine. The differential diagnosis included acute generalized exanthematous pustulosis (AGEP), drug reaction with eosinophilia and systemic symptoms (DRESS), and AGEP-DRESS overlap.