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

Ashley Marsden, Senior Medicines Optimisation Pharmacist, Pharmacy Practice Unit, Royal Liverpool HospitalPublished 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.

UK Health Security Agency (UKHSA – formerly known as PHE) 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.

Below is a summary of knowledge about suitability for vaccination based on previous allergy status.

First dose of COVID-19 vaccine allergy

Only a very small number of individuals have experienced anaphylaxis when receiving a COVID-19 vaccine. Allergy to a previous dose of Moderna COVID-19 vaccine or any of its components (excipients) may affect suitability for vaccination.

Previous allergic reaction to a component of Moderna vaccine

UK Health Security Agency (UKHSA) Immunisation Against Infectious Disease (the Green Book) provides the following information :

  • individuals with a history of prior systemic anaphylaxis reaction to any component of the Moderna vaccine e.g. polyethylene glycol should not receive it (except with expert advice).
  • If recommended by an expert Moderna vaccine can be given under medical supervision in a hospital setting with full resuscitation facilities. A 30 minute observation period is recommended.

Previous reaction to Moderna vaccine

UK Health Security Agency (UKHSA) Immunisation Against Infectious Disease (the Green Book) provides the following information :

  • for individuals with a previous systemic anaphylaxis reaction to Moderna vaccine seek advice from an allergy specialist. Many individuals do not react when given a dose of the same vaccine. A further dose of Moderna vaccine can be considered if recommended by an expert, but this dose must be given under medical supervision in a hospital setting with full resuscitation facilities. A 30 minute observation period is recommended.
  • for individuals without any objective signs of anaphylaxis and for whom symptoms rapidly resolved (with no more than 1 dose of IM adrenaline), a further dose of Moderna vaccine can be given in any vaccination setting.
  • individuals with non-allergic reactions (vasovagal episodes, non-urticarial skin reaction or non-specific symptoms) can receive further doses of Moderna vaccine in any vaccination setting.

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  manufacturer’s information states that a hypersensitivity to any of the excipients present in the Moderna vaccine is a contraindication to the vaccine use.

Excipients present

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

  • Lipid SM-102 = (heptadecan-9-yl 8-{(2-hydroxyethyl)[6-oxo-6-(undecyloxy)hexyl]amino}octanoate)
  • Cholesterol
  • DSPC = 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC)
  • PEG2000-DMG = 1,2-Dimyristoyl-rac-glycero-3-methoxypolyethylene glycol-2000
  • Trometamol
  • Trometamol hydrochloride
  • 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.

Since the COVID-19 Vaccine Moderna contains PEG, use in individuals with PEG allergy is contra-indicated according to the manufacturer’s information.  UK Health Security Agency (UKHSA) 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 a known allergy to PEG is rare. But, undiagnosed PEG allergy should be considered in those with:

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

Managing patients with known or possible PEG allergy

Seek advice of an allergy specialist as recommended by the Green Book

Guidance if allergy specialist recommends vaccination

The Green Book  advises Moderna should be administered in a setting with full resuscitation facilities (e.g. a hospital). 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.

Evidence to support vaccination

The Green Book  advises that there is now evidence that many individuals with initial apparent allergic reactions to an mRNA vaccine can tolerate a second dose of the same vaccine.  Published data for the Pfizer-BioNTech vaccine shows that some individuals with prior allergic reaction to PEG-containing medicines (e.g. PEG-asparaginase) can tolerate the PfizerBioNTech vaccine (although the historical reaction may have been due to a non-PEG component).

Considering AstraZeneca vaccine as an alternative

The Green Book  advises that AstraZeneca vaccine can be used as an alternative vaccine (unless otherwise contraindicated) for individuals with known or possible PEG allergies. The vaccine 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.

The rate of anaphylaxis reported to date after AstraZeneca vaccine is in line with the expected rate of anaphylaxis to non-COVID vaccines. The AstraZeneca vaccine does not contain PEG but does contain a related compound called polysorbate 80. Rarely, 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 (including the adjuvanted influenza vaccine, Fluad® and the GlaxoSmithKline vaccine Fluarix®) are likely to tolerate the AstraZeneca vaccine.

Medicines allergy

UK Health Security Agency (UKHSA) 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 PEG allergy should be considered in the following individuals (see also ‘PEG allergy’ section above).

  • Those with a history of immediate anaphylaxis to multiple, different drug classes 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)
  • a history of idiopathic anaphylaxis

Seek allergy specialist advice regarding PEG allergy if needed (see PEG allergy section for further detail)

See also the UK Chemotherapy board Clinician Frequently Asked Questions (FAQs) and guidance on COVID-19 vaccine for patients receiving Systemic Anti-Cancer Therapy (May 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.

The Children’s Cancer and Leukaemia group have produced advice for children who may be receiving PEG containing drugs.

Antibiotics

UK Health Security Agency (UKHSA) 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

UK Health Security Agency (UKHSA) 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 UK Health Security Agency (UKHSA) 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 manufacturer’s information.

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 UK Health Security Agency (UKHSA) Immunisation Against Infectious Disease (the Green Book).

Change history

  1. Page, tool and image updated to reflect changes in green book regarding management of those with prior allergy to vaccine and PEG. Links updated.
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