Advising individuals with allergies on their suitability for Pfizer-BioNTech COVID-19 Vaccine

Eimear Maguire, Senior Medicines Information Pharmacist, North West Medicines Information CentrePublished Last updated See all updates

Advice on whether people with a previous allergic reaction can have the Pfizer-BioNTech COVID-19 vaccine.

Background

Individuals due to be vaccinated may have had previous allergies, and may ask their healthcare professional for advice on their suitability for vaccination.

Public Health England’s Immunisation Against Infectious Disease (the Green book) states that:

  • those with allergies, including anaphylaxis, to a food, insect sting or most medicines (where the trigger has been identified), can proceed with vaccination as normal according to local guidelines, as long as they are not known to be allergic to any component (excipient) of the vaccine;
  • anyone with a family history of allergies, a previous non-systemic reaction to a vaccine, hypersensitivity to non-steroidal anti-inflammatory drugs (e.g. aspirin, ibuprofen) or mastocytosis can proceed with vaccination as normal, according to local guidelines.

First dose of Pfizer-BioNTech COVID-19 vaccine or other medicines allergy

Allergy to a previous dose of Pfizer-BioNTech COVID-19 vaccine or other medicines may affect suitability. Public Health England’s Immunisation Against Infectious Disease (the Green book) states that:

  • Individuals with a prior history of systemic allergic reaction (including immediate-onset anaphylaxis) to a previous dose or any component of the Pfizer-BioNTech vaccine should not receive it.
  • Individuals with a prior history of systemic allergic reaction (including immediate-onset anaphylaxis) to the first dose of the Moderna vaccine should not receive the Pfizer-BioNTech vaccine. These patients should be referred to an allergy specialist.
  • Individuals with a history of immediate onset-anaphylaxis to multiple classes of drugs or an unexplained anaphylaxis should not be vaccinated with the Pfizer-BioNTech vaccine, except on the advice of an allergy specialist. The AstraZeneca vaccine can be used as an alternative (if not otherwise contraindicated), particularly if they previously tolerated an injected influenza vaccine. The vaccine should be administered in a setting with full resuscitation facilities (e.g. a hospital), and a 30 minute observation period is recommended.

The British Society for Allergy and Clinical Immunology (BSACI) has advised that individuals who have had a possible reaction to the first dose of a COVID-19 vaccine may be able to receive a second dose of vaccine, as per the management advice below:

If symptoms began within 2 hours of the first vaccination, this could indicate an immediate-type allergic reaction:

  • If the patient had systemic symptoms (including anaphylaxis), advice from an allergy specialist should be sought prior to second vaccination.
  • If the reaction involved swelling or rash local to injection site only, the individual can have the second dose using the same vaccine in any vaccination setting; observe for 30 minutes.

If symptoms began 2 or more hours after the first vaccination, this could indicate delayed urticaria/angioedema:

  • If the reaction involved swelling or rash local to injection site only, the individual can have the second dose using the same vaccine in any vaccination setting; observe for 30 minutes.
  • If the reaction was self-limiting or resolved with oral antihistamine, the individual can have the second dose using the same vaccine in any vaccination setting; consider pre-treatment with a non-sedating antihistamine, 30 minutes prior to second vaccination.
  • If the reaction required medical attention, advice from an allergy specialist should be sought prior to second vaccination.

Individuals with non-allergic reactions (vasovagal episodes, non-urticarial skin reaction or non-specific symptoms) to the first dose of a COVID-19 vaccine can receive the second dose of vaccine in any vaccination setting.

See the Figure below for a pictorial representation of this advice: “Flowchart for managing patients who have allergic reactions to the first dose of COVID-19 vaccine”, reproduced with kind permission from the authors of Public Health England’s Immunisation Against Infectious Disease (the Green book).

Excipients

Allergy because of the presence of excipients is possible, with polyethylene glycol of particular importance.

The information for healthcare professionals states that a hypersensitivity to any of the excipients is a contraindication to the vaccine use.

Excipients present

The excipients listed in the manufacturer’s information are as follows:

  • ALC-0315 = (4-hydroxybutyl) azanediyl)bis (hexane-6,1-diyl)bis(2-hexyldecanoate)
  • ALC-0159 = 2-[(polyethylene glycol)-2000]-N,N-ditetradecylacetamide
  • 1,2-Distearoyl-sn-glycero-3-phosphocholine
  • cholesterol
  • potassium chloride
  • potassium dihydrogen phosphate
  • sodium chloride
  • disodium hydrogen phosphate dihydrate
  • sucrose
  • water for injections

Polyethylene glycol (PEG) allergy

Individuals with polyethylene glycol (PEG) allergy should not receive the Pfizer-BioNTech vaccine according to the information for healthcare professionals.

The Pfizer-BioNTech COVID-19 vaccine contains PEG (also called macrogols), a known allergen commonly found in medicines and also in household goods and cosmetics. Medicines containing PEG include some tablets, laxatives, depot steroid injections, and some bowel preparations used for colonoscopy.  Public Health England’s Immunisation Against Infectious Disease (the Green Book) advises that a known allergy to PEG is extremely rare but would contraindicate receipt of this vaccine; however, it is unclear whether PEG is the only cause of allergic reactions in patients with systemic allergic symptoms after the first dose of the Pfizer-BioNTech vaccine.

Patients with undiagnosed PEG allergy may have a history of unexplained (idiopathic) anaphylaxis or of anaphylaxis to multiple classes of drugs; PEG allergy is therefore a possibility in:

  • Individuals with a history of immediate anaphylaxis to multiple different drug classes, with the trigger unidentified;
  • Individuals with a history of anaphylaxis to a vaccine, injected antibody preparation or a medicine likely to contain PEG (e.g. depot steroid injection, laxative);
  • Individuals with a history of idiopathic (unexplained) anaphylaxis.

People who fall into the above groups should be discussed with an allergy specialist prior to vaccination; consider observation for 30 minutes if vaccination proceeds; some patients may benefit from pre-treatment with antihistamine – however, this may mask initial symptoms of a reaction.

Public Health England’s Immunisation Against Infectious Disease (the Green Book) also advises that the AstraZeneca vaccine does not contain PEG and may be used as an alternative in people who are allergic, particularly in individuals who have previously tolerated an injectable influenza vaccine. Whilst the AstraZeneca vaccine does not contain PEG, it contains a compound called polysorbate 80 (see AstraZeneca information for healthcare professionals); some people with PEG allergy may also be allergic to polysorbate 80. However, polysorbate 80 is widely used in medicines and foods, and is present in many medicines including monoclonal antibody preparations. Some injected influenza vaccines (including the main vaccine used in over 65 year olds) contain polysorbate 80. Individuals who have tolerated injections that contain polysorbate 80 (such as certain influenza vaccines) are therefore likely to tolerate the AstraZeneca  COVID-19 vaccine.

Polysorbate 80 allergy

The Pfizer-BioNTech COVID-19 vaccine does not contain polysorbate 80, according to the information for healthcare professionals.

However, the BSACI advise in their COVID-19 Vaccinations and Allergies FAQ that polysorbate 80 is quite similar in structure to PEG, therefore individuals with confirmed polysorbate 80 allergy should discuss this with an allergy specialist/ immunologist before receiving the Pfizer-BioNTech COVID-19 vaccine. Patients with a confirmed polysorbate 80 allergy will have been diagnosed by an allergy specialist; if there is any doubt over the suitability of an individual patient for a specific COVID-19 vaccine, immunologist advice should be sought.

Other allergy considerations

As well as allergy considerations associated with previous vaccination and to excipients, other considerations are as follows.

Antibiotics

Previous allergy to antibiotics is covered in Public Health England’s Immunisation Against Infectious Disease (the Green book) which states that individuals with previous allergy, including anaphylaxis, to an identified drug can receive the Pfizer-BioNTech COVID-19 vaccine.
The manufacturer’s information about antibiotic content states that:

  • Kanamycin is used during the manufacturing process of one of the raw materials used in the vaccine production; however it is not expected to be in detectable quantities in the final product presentation.
  • No other antibiotics (such as penicillins, sulphonamides and neomycin) are used during the manufacturing process.
  • They cannot guarantee that minute amounts of substances are not contained in raw materials obtained from their suppliers.

Foods

Previous allergy to foods is covered in Public Health England’s Immunisation Against Infectious Disease (the Green book) which states that individuals with previous allergy to food, including anaphylaxis, can receive the Pfizer-BioNTech COVID-19 vaccine.

Egg content

The manufacturer states that eggs are not used during the manufacturing of the vaccine and the final product does not contain eggs. However, the manufacturer cannot guarantee that minute amounts of substances, such as egg, are not contained in raw materials obtained from their suppliers.

Gluten content

The manufacturer states that gluten is not used during the manufacturing of the vaccine and the final product does not contain gluten. However, the manufacturer cannot guarantee that minute amounts of substances, such as gluten, are not contained in raw materials from their suppliers.

Nut content

The manufacturer states that nuts are not used during the manufacturing of the vaccine, and the final product does not contain nuts. However, the manufacturer cannot guarantee that minute amounts of substances, such as nuts, are not contained in raw materials obtained from their suppliers.

Soy content

The manufacturer states that soy is not used during the manufacturing of the vaccine and the final product does not contain soy.  However, the manufacturer cannot guarantee that minute amounts of substances, such as soy, are not contained in raw materials obtained from their suppliers.

Latex

Our view is that the risks associated with previous latex allergy are low. The vaccine can be considered not to contain latex and poses the same minimal risk as other injectable medicines presented in vials with a bromobutyl rubber stopper.

This view is formed from:

  • Public Health England’s COVID-19 Vaccination Programme Information for Healthcare Professionals advice that the rubber stopper of each multidose vial of Pfizer-BioNTech vaccine consists of bromobutyl, and does not contain latex.
  • Pfizer Medical Information advice that latex is not used as a raw material during the routine manufacturing process or as an excipient during vaccine formulation. (Although they cannot guarantee that minute amounts of latex are not contained in raw materials obtained from their suppliers and cannot guarantee that the product has not come into contact with latex during the manufacturing process.)
  • Information in The Green Book (chapter 6), which includes advice on managing vaccine choice in patients with severe (i.e. anaphylactic) allergy to latex, would categorise the Pfizer-BioNTech vaccine as not containing latex. 

However, even if the components of an injection do not contain latex, or latex is not used as a raw material during manufacturing, most manufacturers of injectable products advise they cannot guarantee minute amounts of latex are not contained in raw materials obtained from their suppliers or the product has not come into contact with latex during the manufacturing process.

Patients with an allergy to latex can be directed to the Anaphylaxis Campaign website for information.

Other drugs

Public Health England’s Immunisation Against Infectious Disease (the Green book) states that individuals with previous allergy to an identified drug, including anaphylaxis, can receive the Pfizer-BioNTech COVID-19 vaccine. However, it also states that the following individuals should be discussed with an allergy specialist, prior to vaccination:

  • Those with a history of immediate onset-anaphylaxis to multiple classes of drugs with the trigger unidentified (this may indicate PEG allergy).
  • Those with a history of anaphylaxis to a vaccine, an injected antibody preparation or a medicine likely to contain PEG (e.g. depot steroid injection, laxative).

If vaccination proceeds with the Pfizer-BioNTech vaccine (after gaining advice from an allergy specialist):

  • Consider observation for 30 minutes;
  • Some patients may benefit from pre-treatment with an antihistamine; however, this may mask initial symptoms of a reaction.

“Sulfa” medicines

Individuals with previous allergy, including anaphylaxis, to “sulfa” medicines can receive the Pfizer-BioNTech COVID-19 vaccine.

The manufacturer’s information states that sulphonamide antibiotics are not used in the manufacturing process of the Pfizer-BioNTech COVID-19 vaccine. Additionally, there are no non-antibiotic “sulfa” drugs listed as an excipient in section 6.1 of the manufacturer’s information.

Thiomersal content

The Pfizer BioNTech COVID-19 vaccine does not contain thoimersal, according to the information for healthcare professionals.

Individuals with previous allergy, including anaphylaxis, to thiomersal can receive the Pfizer-BioNTech COVID-19 vaccine.

Public Health England’s Immunisation Against Infectious Disease (the Green book) highlights that thiomersal is a mercury based compound used as a preservative in the manufacture of some vaccines for many years and has been associated with some safety concerns. However, this vaccine is preservative-free and therefore does not contain thiomersal.

Summary of allergy considerations

The table below is a pictorial summary of the management of patients with a history of allergy, reproduced with kind permission from authors of Public Health England’s Immunisation Against Infectious Disease (the Green book).

Also of interest

Managing anaphylaxis in the COVID-19 vaccination setting

29 December 2020Advice on managing anaphylaxis in the vaccination setting with specific reference to COVID-19 vaccines.

Change history

  1. Added "Flowchart for managing patients who have allergic reactions to the first dose of COVID-19 vaccine" to "First dose of AstraZeneca COVID-19 vaccine or other medicines allergy" section; added a new section "Summary of allergy considerations", including a summary table.

  2. Updated to reflect changes in the Green Book: "Background" section updated; "First dose of Pfizer-BioNTech COVID-19 vaccine or other medicines allergy" section updated, including addition of BSACI management advice for people who had a reaction to the first dose of vaccine; significant updates to "Polyethylene glycol (PEG) allergy" section; added which patients should be discussed with an allergy specialist prior to vaccination in the "other drugs" section.

  3. Changes made to include page as part of a series covering similar topics

  4. Changes made to clarify advice in relation to other allergy considerations, including addition of advice regarding latex

  5. Changes made to clarify advice in relation to allergies and excipients

  6. Added link to BSACI in PEG/polysorbate 80 section

  7. Polysorbate 80 information added.

  8. PEG section modified, based on updated information from the Green Book.

  9. Published