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I have a patient who is allergic by patch testing to polyethylene glycol. She is very afraid of receiving the mRNA vaccines because they contain this chemical. I have the possibility of obtaining a dose of one of the mRNA vaccines to use in testing her. Is there a protocol for skin testing to the vaccine? Are there data on sensitivity and specificity of such skin testing?


Only one (oral PEG allergy) had a positive skin test (not patch test) to PEG and that patient tolerated the Janssen vaccine. The other 15 were skin test negative and tolerated the first dose of a mRNA vaccine. Another recent publication with small numbers of patients (n=15) suggests no utility in skin testing vaccine reactors, and that those with a history of PEG allergy can tolerate the mRNA vaccines. (2)

The AAAAI position on COVID Vaccine and component testing is that it is of unclear utility in evaluating possible allergic reactions to these vaccines. The validity of this approach has not been proven, nor have non-irritant concentrations been determined. Further, from a public health standpoint, the stock of vaccines is limited and (at this time) is likely better used for vaccinations rather than evaluation of potential reactions.

With your patient’s history of being patch test positive for PEG, if she has tolerated other vaccines that contain polysorbate, then the Janssen vaccine may be a better option. I would recommend shared decision making with a thorough discussion of risk-benefit ratio. Note, that there have been reports of individuals having positive skin testing to the vaccine (Moderna), who have been able to receive the Moderna vaccine without significant problems (one had a mild case of acute urticaria post vaccination that rapidly resolved). (2) Further, bringing into question the utility of skin testing for these mRNA vaccine reactions.

1) Banerji A, Wolfson AR, Wickner PG, Cogan AS, McMahon AE, Saff R, Robinson LB, Phillips E, Blumenthal KG. COVID-19 Vaccination in Patients with Reported Allergic Reactions: Updated Evidence and Suggested Approach. J Allergy Clin Immunol Pract. 2021 Apr 15:S2213-2198(21)00439-6. doi: 10.1016/j.jaip.2021.03.053. Epub ahead of print. PMID: 33866033; PMCID: PMC8049186.

2) Pitlick MM, Sitek AN, Kinate SA, Joshi AY, Park MA. Polyethylene glycol and polysorbate skin testing in the evaluation of coronavirus disease 2019 vaccine reactions: Early report. Ann Allergy Asthma Immunol. 2021 Mar 26:S1081-1206(21)00188-5. doi: 10.1016/j.anai.2021.03.012. Epub ahead of print. PMID: 33775902; PMCID: PMC7997158.

3) Mustafa SS, Ramsey A, Staicu ML. Administration of a Second Dose of the Moderna COVID-19 Vaccine After an Immediate Hypersensitivity Reaction With the First Dose: Two Case Reports. Ann Intern Med. 2021 Apr 6:L21-0104. doi: 10.7326/L21-0104. Epub ahead of print. PMID: 33819057; PMCID: PMC8033634.

I hope you find this helpful. I appreciate Dr. Mitch Grayson’s input on this response.

Respectfully submitted,
Jeffrey G Demain, MD, FAAAAI

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