Allergic Reactions to the COVID-19 vaccine (ARCOV) study: the McGill University Health Center (MUHC) experience.

Abstract

mRNA-COVID-19 vaccines have been associated with allergic reactions. A history of anaphylaxis has been suggested as a risk factor for such reactions. Polyethylene glycol (PEG) has been proposed as a possible culprit allergen. To investigate possible PEG or polysorbate allergy among patients reporting prior reactions to COVID-19 vaccines or PEG, and to report their subsequent tolerance of COVID-19 vaccines. From January 1 st to October 31 st, 2021, adult patients referred to the MUHC allergy clinics who were considered at risk of anaphylaxis were prospectively recruited. The entry criteria were any documented history of reaction to a COVID-19 vaccine or reported allergy to PEG or polysorbate. Evaluated patients underwent skin-prick-testing (SPT) with PEG and polysorbate. Following SPT, placebo-controlled vaccine challenges were carried out. Of the 44 patients recruited, 40 (90.1%) had reacted to the first vaccine dose, 18 (45%) of them had anaphylactic reaction. All patients underwent SPT and 5 (11.3%) had a positive test. Thirty-nine patients (88.6%) underwent COVID-19 vaccine challenge at the allergy clinic. The majority tolerated the vaccine, 18 (40.1%) received a single full-dose, 20 (45.4%) 2-split-doses and 6 (13.6%) using a graded dosing protocol. Two out of the 40 patients who reacted to 1 st dose, had immediate non-severe allergic reactions to the second dose. In this cohort of patients with a history of anaphylaxis and increased risk of allergic reactions to the COVID-19 vaccines, following allergist evaluation, including negative PEG skin testing, the vaccine was safely administered without any serious adverse events.