Initial concerns for people with allergies were alleviated three weeks after being raised, when guidance by the MHRA was reversed. Two healthcare workers had been reported to have suffered anaphylactic reactions to their Pfizer vaccines in the first week of the COVID-19 vaccine roll-out in December 2020. But, on investigation, there was no scientific basis for concern for the large majority of individuals with food, venom (bees and wasps) or known medicine allergies, even if they had experienced anaphylaxis before.
Unfortunately, the message that Pfizer was not suitable for people with allergies, and in particular for people with any history of anaphylaxis, spread far and wide. It has proved extremely difficult to correct this message. When the Oxford AstraZeneca vaccine was authorised, people with any allergy whatsoever were frequently told that AstraZeneca was more suitable and safer for them. So they received their two doses of that vaccine instead. This was despite the guidance by that time being very clear that there was NO REASON for them to fear the Pfizer vaccine.
People are still being turned away from vaccination centres because they report a history of anaphylaxis to food, venom, or to an identified medicine. It seems that they are often wrongly informed they need AstraZeneca as a booster, which has been noted as being less effective against COVID-19 than the Pfizer booster. The AstraZeneca vaccine is also difficult to arrange as a booster and is not usually offered in booster clinics. As a result, the charities report that patients often end up running round in circles between their GP and 119 operators, who frequently are unable to offer any guidance.
The ingredient in the Pfizer vaccine that originally caused concern is called polyethylene glycol (PEG for short, and also known as Macrogol). It is a common ingredient in medicines. Most allergic reactions caused by PEG have resulted from laxatives and some types of steroid injections. However, it is an extremely rare cause of anaphylactic reactions and ONLY individuals with a history of anaphylaxis immediately after taking medicines containing PEG need to seek further specialist allergy advice before vaccination.
As the vaccine roll-out has continued, studies have shown that even people known or suspected to have an allergy to PEG can be safely vaccinated with the Pfizer vaccine. There is just ONE case report in the medical literature of anaphylaxis with the Pfizer vaccine caused by PEG.
Key messages for patients
- You CAN have a Pfizer or Moderna booster if:
- you have any type of FOOD allergy (including anaphylaxis)
- you have had anaphylaxis to WASP or BEE stings
- you have an identified allergy to most medicines
- any current or recent medications that you have taken safely contain Polyethylene glycol (PEG/Macrogol)
- You do need to seek further allergy advice if you have had immediate anaphylaxis to MULTIPLE unrelated medicines that contain Polyethylene glycol (PEG/Macrogol). You can check ingredients of medicines at medicines.org.uk if you are not sure.
Allergy UK Resources
Anaphylaxis Campaign Resources
Allergy to Polyethylene Glycols Factsheet
British Society for Allergy and Clinical Immunology