Cutaneous reactions reported post COVID-19 trials range from acute and immediate to delayed reactions. The suspected trigger for hypersensitivity reactions is the inactive ingredients, such as polyethylene glycol in mRNA vaccines and polysorbate 80 in AstraZeneca. Localised or injection- site reactions are generally self-limiting and occur within seven days. Younger and female patients were more likely to report injection-site reactions, and most cutaneous reactions after the second dose occurred sooner than after the first dose. Delayed large local reactions or ‘COVID arm’ have been reported after seven days post vaccination and generally resolve within two weeks. However, there were cases reported four days post-AstraZeneca vaccination. Other dermatological reactions, such as pityriasis rosea- like eruptions and flares of existing cutaneous conditions were seen in mRNA and AstraZeneca recipients but not in Sinopharm. Risk stratifying vaccine recipients into low, medium or high risk of developing severe allergic reactions may be done using screening questions. Skin testing may be considered for the high risk category but negative skin testing does not rule out a subsequent allergic response. Delayed cutaneous reactions may be misdiagnosed as cellulitis and administered unnecessary antibiotics.

Keywords: Cellulitis, COVID-19, COVID-19 vaccines, delayed hypersensitivity, drug eruptions

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