Polythylene glycol severe allergy and SARS-CoV-2 vaccines: usefulness of testing with PEG 1500 extract

Show more: Authors information and Publication history
Authors Information

1Department of Immunoallergy, Hospital da Luz Lisboa, Lisbon, Portugal
2Comprehensive Health Research Center (CHRC), NOVA Medical School Research, Universidade Nova de Lisboa, Lisbon, Portugal 


Published: 02 December 2022
Accepted: 25 November 2022
Received: 06 October 2022


Background. Polyethylene glycol (PEG) is being used for first time as an excipient for mRNA anti-SARS-CoV-2 vaccines containing PEG 2000, highlighting it as a potential cause of anaphylaxis. Methods.  We evaluated 126 patients with moderate-high risk of allergy to SARS-CoV-2 vaccines referred to our department from March-December 2021. Skin tests were performed with PEG 1500 extract (Roxall), using a stepwise approach, with readings at 30 minutes: prick tests with 0.1%, 1% and 10% concentrations; if negative, intradermal tests with 0.0001%, 0.001% and 0.01% concentrations. The same protocol was applied to 5 healthy controls. Results. Six patients had positive immediate intradermal tests with PEG 1500, all with severe PEG allergy: one with a near-fatal anaphylaxis after glucocorticoid injection containing PEG 3350 and five with systemic allergic reactions after mRNA vaccines containing PEG 2000 (Pfizer-BioNTech or Moderna). One patient developed anaphylaxis during intradermal test. These six patients were negative to polysorbate 80.The remaining 120 patients had negative tests to PEG 1500; seven had positive tests to polysorbate 80. All controls had negative tests. Conclusions. To our knowledge this is the first study describing the allergy work-up testing with PEG1500 commercial extract in the scope of SARS-CoV-2 vaccination. The algorithm designed for skin tests revealed to be a useful tool. Severe PEG allergy was diagnosed in 5% of patients, contraindicating PEG-containing vaccines. PEG allergy was excluded in one hundred patients that afterwards took SARS-CoV-2 vaccines containing PEG 2000. Investigation should be conducted in specialized drug allergy centers.

Anaphylaxis; COVID-19 vaccine; drug allergy; PEG allergy; skin testing.   

Table of Content: Vol. 55 (No. 6) 2023 November

European Annals of Allergy and Clinical Immunology ISSN 1764-1489 | © 2024