Abstract
BackgroundCoronavirus disease 2109 (COVID-19) vaccines have recently been approved to curb the global pandemic. The risk of allergic reactions to the vaccine polyethylene glycol (PEG) component has raised significant public concern. Desensitization is suggested in cases of vaccine related hypersensitivity reactions. After comprehensive literature review on the topic, our aim was to establish a safe and effective desensitization protocol for patients with suspected or confirmed immediate type hypersensitivity reactions to the COVID-19 vaccine.MethodsParticipants were referred to the McGill University Health Center (MUHC) Allergy-Immunology department for clinical evaluation following a reported reaction to their first dose of Moderna® mRNA-1273 or Pfizer-BioNTech® BNT162b2 vaccines. They underwent skin prick testing (SPT) with higher and lower molecular weight (MW) PEG and polysorbate 80, as per published protocols. Their second dose was administered following a desensitization protocol consisting of multiple dose-administration steps followed by a 60-min observation period.ResultsAmong a cohort of 142 patients with an increased risk for allergic reactions to the COVID-19 vaccines, six individuals were selected to undergo desensitization. All were female with allergic background including chronic spontaneous urticaria, anaphylaxis to medications, and/or vaccines. The main symptom after their first dose was difficulty swallowing with lightheadedness or immediate urticaria, angioedema, and/or dizziness. Two patients had positive skin testing. One patient was on chronic antihistamines which resulted in an inconclusive PEG skin test and the skin testing was negative for the three other patients. During the desensitization, two patients reported cutaneous symptoms of an immediate reaction and were managed with antihistamines. One of these patients also complained of ear pressure and had a drop in her systolic blood pressure, treated with intravenous fluids.ConclusionThis study suggests that some individuals with an immediate-type hypersensitivity reaction to their first dose of mRNA COVID-19 vaccine may safely receive their second dose using a desensitization protocol. The success of this desensitization protocol is a step forward in the fight against COVID-19, allowing more individuals to be immunized.
Highlights
A year and a half after the appearance of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus responsible for the coronavirus disease 2019 (COVID-19) pandemic, there have been more than 260 million cases of infection and over 5 million deaths worldwide [1]
We report the successful desensitization in a cohort of six patients with reported immediate-type COVID-19 vaccine reactions
Half of the patients reported an immediate reaction to the Moderna R mRNA-1273 vaccine and the other half to the Pfizer-BioNTech R vaccine
Summary
A year and a half after the appearance of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus responsible for the coronavirus disease 2019 (COVID-19) pandemic, there have been more than 260 million cases of infection and over 5 million deaths worldwide [1]. The PfizerBioNTech R BNT162b2 and the Moderna R mRNA-1273 vaccines have an innovative mechanism of action involving the use of a lipid nanoparticle-encapsulated mRNA encoding the spike protein of SARS-CoV-2. They both help protect against COVID-19 with a significant efficacy of 95 and 94.1%, respectively [2, 3]. For both vaccines, allergic reactions and anaphylaxis remain rare and the mechanism has not been fully understood. After comprehensive literature review on the topic, our aim was to establish a safe and effective desensitization protocol for patients with suspected or confirmed immediate type hypersensitivity reactions to the COVID-19 vaccine
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