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Allergy Today: The Pfizer Vaccine and PEG Allergy

Dr Miriam Hurst runs the high-risk vaccine clinic at Auckland Public Health (APH). She is also a clinical immunology allergy specialist and pathologist at Auckland District Health Board (ADHB). Here, she shares details of her work...

The high-risk clinic is for people who had anaphylaxis to the first dose of the vaccine and/or to PEG, (polyethylene glycol, also known as macrogol), which is used to manufacture the Pfizer vaccine. Currently anaphylaxis or allergy to PEG is listed as a contraindication to the Pfizer vaccine, which contains a small amount of PEG2000.iStock-1139629383-24

A lot of people who are anxious about the vaccine and/or concerned there is a medical reason not to have it, are being referred to the clinic for PEG allergy.

Most of them are concerned because they've had contact reactions to various cosmetics, personal care products etc; but Dr Hurst says these symptoms are not remotely concerning in relation to the vaccine.

PEG anaphylaxis (which is rare) is almost always with the high molecular weight PEGs in bowel prep (PEG3350) and pegylated medications (PEG5000), although some oral medications (e.g. Augmentin & omeprazole) also contain high molecular weight PEGs. Most people who react to high molecular weight PEG are fine with low molecular weights. Cosmetics, toothpastes, creams etc usually contain PEGs of <1000. PEG has never been used in a vaccine before the mRNA COVID-19 vaccines so patients with anaphylaxis to other vaccines will not have had this due to PEG.

Many reactions to PEG and to the vaccine may not be IgE-mediated and therefore testing (skin prick or blood test) is not helpful.

Patients with known PEG anaphylaxis can be safely given the vaccine at the hospital. The high-risk clinic has done nine so far, with no anaphylaxis; any side effects were minor and settled with medication. The other vaccines approved for use in NZ – AstraZeneca, Novavax, and Janssen, do not contain PEG and could also be used once available.

The high risk clinic is also successfully revaccinating those with anaphylaxis to the first dose.

The overall message is that the Pfizer vaccine is safe for people whether or not they have allergic conditions including a history of anaphylaxis to a substance.
 

Miriam Hurst, MBChB, FRACP, FRCPA

 

Clinical Immunologist/Immunopathologist

Service Lead Clinician

Auckland Hospital

Allergy Today, October 2021