Patients with previous immediate hypersensitivity reactions to polyethylene glycol can safely receive the BNT162b2 mRNA COVID-19 vaccine

Abstract

Previous anaphylaxis or immediate allergic reaction to polyethylene glycol (PEG; also known as macrogol) is considered a contraindication to the BNT162b2 mRNA COVID-19 vaccine, which contains 50 ug of PEG at a molecular weight of 2000, and this component is thought to account for the higher rate of anaphylaxis seen with this vaccine (4.7 per million doses) than with other non-mRNA vaccines. However, there is evidence that both anaphylaxis to PEG and anaphylaxis to the Pfizer COVID-19 reaction may not be IgE-mediated, with patients with anaphylaxis to first dose of the Pfizer COVID-19 vaccine receiving their second dose of vaccine without no or milder reactions in a high-risk clinic setting. In New Zealand, non-PEG-containing COVID-19 vaccines were not available until late 2021. Therefore, we offered patients with known or suspected PEG anaphylaxis their first dose of Pfizer COVID-19 vaccine in a high-risk hospital clinic. Eleven patients with previous hypersensitivity to PEG (including eight with anaphylaxis) successfully received their first dose with mild or no reactions; all have now had their second doses in the community without significant reaction. Record review also showed that most patients with previous hypersensitivity reactions to pegylated asparaginase have also been successfully vaccinated. This demonstrates that previous PEG hypersensitivity, including anaphylaxis, does not exclude immunisation with the Pfizer COVID-19 vaccine.