To date, there are six reported cases of a severe allergic reaction to the Pfizer/BioNTech COVID-19 vaccine. At this time, approximately 300,000 people have been vaccinated in the United States. All reactions occurred within the initial observation period. These people received epinephrine and they all recovered. While we still do not know exactly what is causing these reactions, one of the likely culprits is polyethylene glycol. This article discusses polyethylene glycol allergy.
What is polyethylene glycol?
Polyethylene glycols (PEGs) are synthetic chemicals that are used frequently in our daily lives. PEGs are in medical products (e.g. wound dressings and laxatives), household products (e.g. detergents and polishes), food (e.g. preservatives and supplements), and cosmetic products (e.g. creams, facial products, and baby wipes).
PEG is used in the COVID-19 vaccine to protect the mRNA in the vaccine. It also helps to penetrate cells to jumpstart your immune system. The ingredients in the Pfizer COVID-19 and Moderna vaccines includes PEG-2000. The number following the PEG refers to the molecular weight of that substance.
How common is PEG allergy?
A review of the scientific literature reported 37 cases of an allergic reaction to PEG from 1977 to 2016. However, only 28 of these cases actually met the criteria for a severe allergic reaction (i.e. anaphylaxis).
Authors from a recently published report on PEG allergy concluded that the risk of developing an allergic reaction increases when the molecular weight of the PEG is high. None of the patients in this report reacted to PEG 2000, which is the molecular weight of PEG in the COVID-19 vaccines.
In other words, a PEG allergy is very rare!
Should I get tested for PEG allergy?
There is no commercially available blood test for PEG allergy at this time. Allergy skin testing to PEG is available. Our office currently does not offer this PEG skin testing. However, testing is usually NOT necessary unless there is a history of a reaction where PEG is a possibility.
Organizations such as the American Academy of Allergy, Asthma, and Immunology (AAAAI), FDA, and CDC are actively looking into these recent reactions. They will create strategies to help reduce the risk of future reactions. The list of people who cannot get the vaccine will narrow if PEG is truly the culprit in these six vaccine reactions.
Oak Brook Allergists will continue to update you with important information regarding COVID-19 vaccines when it becomes available. If you have further questions, please call us at (630) 574-0460 or by filling out our appointment request form online now. We have convenient locations in Downers Grove, Elmhurst, Naperville, and Plainfield, Illinois.