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

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 COVID-19 Vaccine Moderna.

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 COVID-19 vaccine allergy

Allergy to a previous dose of Moderna 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 Moderna COVID-19 vaccine should not receive it.
  • Individuals with a prior history of systemic allergic reaction (including immediate-onset anaphylaxis) to the first dose of the Pfizer-BioNTech vaccine should not receive the Moderna vaccine. These patients should be referred to an allergy specialist.

Seek advice from an allergy specialist regarding the above patients.

Our decision tool below will guide you through treating patients with prior allergy.

COVID-19 Vaccine Prior Allergy Decision Tool

Advice end-points

Given the nature of the previous reaction, you should seek advice from a specialist before proceeding.

The patient can have the second dose using the same vaccination in any vaccination setting.

Observe the patient for 30 minutes after they’ve received the vaccine.

The patient can have the second dose using the same vaccination in any vaccination setting.

Consider pre-treatment with a non-sedating oral antihistamine 30 minutes beforehand.

  • Excipients

Allergy due to any excipient is possible but polyethylene glycol is 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:

  • Lipid SM-102
  • Cholesterol
  • 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC)
  • 1,2-Dimyristoyl-rac-glycero-3-methoxypolyethylene glycol-2000 (PEG2000-DMG)
  • Trometamol (Tris)
  • Trometamol hydrochloride (Tris HCl)
  • Acetic acid
  • Sodium acetate trihydrate
  • Sucrose
  • Water for injections

The vaccine contains polyethylene glycol (PEG)/macrogol as part of PEG2000-DMG.

Polyethylene glycol (PEG) allergy

Polyethylene glycol (PEG – also known as macrogols) is a known allergen commonly found in medicines and also in household goods and cosmetics.

Moderna COVID-19 vaccine is not suitable where there is prior PEG allergy

Since the COVID-19 Vaccine Moderna contains PEG, individuals with PEG allergy should not receive this vaccine. Public Health England’s Immunisation Against Infectious Disease (the Green Book) advises that individuals who have had a prior allergic reaction to PEG should be referred to an allergist prior to vaccination.

The Green Book advises that as the AstraZeneca COVID-19 vaccine does not contain PEG, it may be used (unless otherwise contraindicated) as an alternative in people who are PEG-allergic.
However, whilst the AstraZeneca vaccine does not contain PEG, it does contain a compound called polysorbate 80 (see AstraZeneca information for healthcare professionals). Some people with PEG allergy may also be allergic to polysorbate 80 (which is widely used in medicines and foods). Some injected influenza vaccines (including the main vaccine used in over 65 year olds) contain polysorbate 80. Individuals who have tolerated such injections are therefore more likely to tolerate the COVID-19 Vaccine AstraZeneca and vaccination can proceed:

  • following discussion with an allergy specialist;
  • in a setting with full resuscitation facilities (e.g. a hospital);
  • with a 30 minute observation period is recommended;
  • with pre-treatment with antihistamine where necessary (although note that this may mask initial symptoms of a reaction).

Be aware of patients with undiagnosed PEG allergy

Patients with undiagnosed PEG allergy may have a history of unexplained (idiopathic) anaphylaxis or of anaphylaxis to multiple classes of drugs (see also “Medicines allergy” below). PEG allergy is therefore a possibility in individuals with a history of:

  • immediate anaphylaxis to multiple different drug classes, with the trigger unidentified;
  • anaphylaxis to a vaccine, injected antibody preparation or a medicine likely to contain PEG (e.g. depot steroid injection, laxative, some bowel preparations used for colonoscopy);
  • idiopathic (unexplained) anaphylaxis.

People who fall into the above groups should be discussed with an allergy specialist prior to vaccination. Public Health England’s Immunisation Against Infectious Disease (the Green Book) advises that the AstraZeneca vaccine may be used as an alternative in such people, particularly in individuals who have previously tolerated an injectable influenza vaccine. If vaccination proceeds following discussion with an allergy specialist, it should be administered in a setting with full resuscitation facilities (e.g. a hospital), and a 30 minute observation period is recommended; some patients may benefit from pre-treatment with antihistamine – however, be aware that this may mask initial symptoms of a reaction.

Polysorbate 80 allergy

The Moderna COVID-19 vaccine does not contain polysorbate 80, according to the information for healthcare professionals. However, it would be prudent to discuss these individuals with an allergy specialist prior to vaccination.

Medicines allergy

Public Health England’s Immunisation Against Infectious Disease (the Green book) states that individuals with previous allergy to a medicine (where the trigger has been identified), including anaphylaxis, can receive the Moderna COVID-19 vaccine. People with hypersensitivity to nonsteroidal anti-inflammatory drugs e.g. aspirin, ibuprofen, can also receive the Moderna COVID-19 vaccine. However, the Green Book also states that the following individuals should be discussed with an allergy specialist, prior to vaccination (this may indicate PEG allergy; see also “PEG allergy” section above):

  • Those with a history of immediate onset-anaphylaxis to multiple classes of drugs with the trigger unidentified.
  • 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 Moderna 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.

See also the UK Chemotherapy board Clinician Frequently Asked Questions (FAQs) and guidance on COVID-19 vaccine for patients receiving Systemic Anti-Cancer Therapy (February 2021).  This has been produced in response to questions about use of COVID-19 vaccines in patients who have experienced a reaction to systemic anti-cancer therapy (SACT) or excipients of SACT.

Antibiotics

Public Health England’s Immunisation Against Infectious Disease (the Green book) states that individuals with previous allergy to a medicine (where the trigger has been identified), including anaphylaxis, can receive the Moderna COVID-19 vaccine.

“Sulfa” medicines

Public Health England’s Immunisation Against Infectious Disease (the Green book) states that individuals with previous allergy to a medicine (where the trigger has been identified), including anaphylaxis, can receive the Moderna COVID-19 vaccine.

Other allergy considerations

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

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 Moderna COVID-19 vaccine.

The  manufacturer’s information does not list the presence of any:

  • Egg
  • Gluten
  • Nut
  • Soy

However, note that most manufacturers cannot guarantee that minute amounts of substances, such as the ones listed above, 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 chlorobutyl rubber stopper.

This view is formed from:

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.

Thiomersal content

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

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).

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