Is there an etiological role for polyethylene glycol (PEG)-2000 in COVID arm due to mRNA vaccines?

ABSTRACT

Background: Delayed local reactions due to mRNA vaccines or COVID arm have been reported. COVID arm commonly presents as an itchy and painful erythematous plaque with swelling and is characterized by a delayed onset of 7 to 10 days after vaccination. New excipients used in mRNA vaccines (polyethylene glycol (PEG)-2000, tromethamol and 1,2-distearoyl-sn-glicero-3-phosphocholine) have increased the awareness about their role in such cutaneous adverse reactions. Objectives: To define the excipient accountability in COVID arm through specific skin provocation testing. Methods: Health workers of a tertiary level hospital suffering COVID arm were patch, skin prick (SP) and intradermal (ID) tested with PEG-400, PEG-2000, tromethamol and 3-phosphocholine at different concentrations (0.001%, 0.01%, 0.1% and 1%). Positive long standing ID reactions were biopsied. Results: Eleven patients were included. Patch tests were always negative. PEG-2000 presented positive SP at 1% (4 patients) and 0.1% (1 patient). PEG-2000 ID was positive at 1% (10 patients), 0.1% (7 patients) and 0.01% (6 patients). Three showed long standing positive reactions to ID of PEG-2000 on day 2, whose biopsies depicted perivascular lymphocytes, occasional eosinophils and dermal edema. In addition, 6 patients reacted to PEG-400, all of which also reacted to PEG-2000. SP and ID for the other excipients were negative. Conclusions: The presence of immediate and delayed reactions to PEG-2000 in patients. with COVID arm poses a challenge on whether PEG-2000 acts as a delayed sensitizer or. these infrequent reactions are irritative.