João Vieira et al.

The Pfizer-BioNTech SARS-CoV-2 vaccine is an mRNA vaccine that uses a lipid-based nanoparticle carrier system, stabilized by polyethylene glycol (PEG) 2000. Although evidence on the pathogenesis of severe immediate reactions to the SARS-CoV-2 vaccine is lacking, the PEG molecule has been proposed as a possible culprit for these reactions due to existing evidence of its ability to cause immunoglobulin E (IgE)-mediated anaphylaxis.

… Assuming the reactions to the Pfizer-BioNTech vaccine resulted from IgE-mediated mechanisms, skin testing might prove a valuable method to identify patients with allergy to the vaccine or its components

… Our aim is to evaluate skin test positivity to the P zer-BioNTech SARS-CoV-2 vaccine and its association with PEG 2000 skin tests and with allergic reactions to the vaccine.

… Skin test positivity to the vaccine was associated to a systemic reaction in 2 of 4 subjects. Although the dimension of our data is limited and does not allow de nitive conclusions, it suggests that skin tests with the vaccine may prove useful to predict immediate reactions to the P zer-BioNTech vaccine.

Only 1 of the 4 skin tests to PEG 2000 had a positive result. This suggests a role of PEG in some immediate reactions to the P zer-BioNTech SARS-CoV-2 vaccine, but it also points out that there may be non-PEG related immediate reactions to the vaccine.