Vaccine allergy

Links of interest

Vaccine Allergy

As with all medication or biological products, people can be allergic to certain vaccines.

Immediate Reactions

Immediate allergic reactions or anaphylaxis to vaccines are rare. These reactions usually start within minutes following the vaccination and are characterized by the same symptoms as immediate reactions to other allergens; skin manifestations (urticaria, swelling, itching), respiratory manifestations (cough, difficulty breathing, wheezing) and a reduction in blood pressure (weakness, loss of consciousness). If a significant immediate allergic reaction is suspected, it must be treated rapidly with epinephrine. It is important that the person suffering from the allergic reaction ultimately be referred to an allergist. Most of the time, allergy testing can confirm the allergy to the vaccine, and the resulting information can be very helpful for future vaccination. In general, most patients allergic to one vaccine in particular can receive other vaccinations without problems.

Late Reactions

When symptoms might be due to an allergy (for example urticaria, redness, itching) but follow several hours or days after having received the vaccination, it is unlikely to be a true allergy to the vaccine.

Local Reactions

Sometimes vaccines can cause important local reactions that begin in the hours following the vaccination or even the next day. The site of vaccination (usually the arm) can become inflamed, red, and painful. The reaction can last several days. Although these reactions can be quite alarming, they are not typically representative of an acute allergic reaction. There is generally no risk of an immediate allergic reaction with the next vaccination. Consultation with an allergist is not necessary. Vaccines containing the booster DT (diphtheria, tetanus) are more often associated with this kind of reaction.

COVID-19 vaccination and allergies

Now that large scale vaccination against COVID has started, some people known to have allergies are wondering if it’s safe to get vaccinated. Although at the beginning of the vaccine campaign in the United Kingdom a recommendation was made to not vaccinate people having severe allergies, this contraindication was removed after analyzing the cases of people having had an allergic reaction to the vaccine. What’s more, even if it seems that vaccination against COVID-19 causes allergic reactions more frequently than other vaccines, the risk remains very low – 11.1 cases of anaphylaxis per million doses, in comparison with 1.3 per million doses for the flu vaccine.

It should be noted that most of the people who were suspected of having an allergic reaction to one of these vaccine tolerated a second dose.

At this moment, concerning allergies, the only contraindication to receiving COVID-19 vaccines is an allergy to their components. The vaccines approved at this time (Pfizer-BioNTech, Moderna, and Nuvaxovid) don’t contain food or animal proteins, antibiotics, preservatives or latex. The vaccines Janssen and AstraZeneca are no longer available.

People suffering from food allergies, even serious ones, respiratory allergies (including asthma), insect allergy, antibiotic allergy or an allergy to anti-inflammatories such as aspirin or ibuprofen, an allergy to latex or to anesthetics can receive the vaccines against COVID-19. The same is true for people suffering from chronic urticaria or angioedema.

Only people with a history of allergy to polyethylene glycol (PEG) should be evaluated by an allergist before receiving a vaccine. PEG is found in many laxatives (eg, Lax-A-Day, RestoroLAX) and in several laxative preparations given prior to a colonoscopy (such as Colyte, golytely, Klean-Prep ou Peglyte ). People having had allergic reactions to these products should consult an allergist before receiving any of the currently approved COVID vaccines.

People with a history of immediate allergy (less than an hour after administration) to vaccines containing polysorbate (including flu vaccines) do not need to consult with an allergist and can be vaccinated at vaccination centres. They will receive the Pfizer-BioNTech or Moderna vaccines, since the Nuvaxovid vaccine contain polysorbate. The observation period after vaccination will be lengthened from 15 to 30 minutes.

People having had an immediate reaction (less than one hour) after receiving a COVID-19 vaccine, or those having a severe reaction in the 24 hours following vaccination must be directed to Public Health for further evaluation.

Note that people who have an autoimmune disease or an immunodeficiency can receive the vaccines approved in Canada against COVID-19. However, it’s possible the COVID-19 vaccines will be less effective in immunosuppressed people. This includes people who suffer from an immunodeficiency or in whom their immune system is weakened by certain medications or illnesses.

Here are links (in French and English) providing the complete list of components of different vaccines against COVID-19:

https://www.msss.gouv.qc.ca/professionnels/vaccination/piq-vaccins/covid-19-vaccin-a-arn-messager-contre-la-covid-19/

https://msss.gouv.qc.ca/professionnels/vaccination/piq-vaccins/covid-19-pra-vaccin-a-proteine-recombinante-avec-adjuvant-contre-la-covid-19/

Recommendations of the National Advisory Committee on Immunization (NACI) concerning allergies:

https://www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci/recommendations-use-covid-19-vaccines.html#t3

Egg Allergy

Certain vaccines use egg embryos during the manufacturing process and so are administered with caution to individuals allergic to eggs.

The vaccine against yellow fever, required when travelling to certain countries, contains egg protein. The risk of allergic reaction is higher with this vaccine than it is with with other egg containing vaccines. A consultation with an allergist is necessary in order to evaluate the risk and to proceed with vaccination if possible. The RRO (or MMR) vaccine (against measles/rougeole, mumps/oreillons and rubella/rubéole ) does not contain a significant quantity of egg protein. It has been known for many years now that this vaccine can be given without particular precautions to egg allergic individuals. An allergy consultation is not necessary and the vaccine can be given in the regular setting for recommended vaccinations.

The annual flu vaccine contains a minimal quanity of egg protein. It has been demonstrated that egg-allergic individuals can receive the flu vaccine without any particular precautions. An allergy consultation is not necessary and the vaccine can be given in the regular settings for recommended vaccinations.

The vaccine Imvamune, against smallpox or MPox is prepared from virus cultivated fibroblast cells from chicken embryos and doesn't contain a significnat amount of egg protein. The vaccine can be administered without particular precautions and a consultation in allergy is not necessary.

The rabies vaccine RabAvert™ is produced from a culture of embryonic chick cells. The rabies vaccine IMOVAX™ doesn't contain egg protein particles. In the case of pre-exposure vaccination, the rabies vaccine IMOVAX™ should be administered to egg-allergic individuals. In the case of post-exposure prophylaxis, it is preferable to use the IMOVAX™ vaccine in egg-allergic individuals. If the IMOVAX™ vaccine is not available, the vaccine RabAvert™ can be administered under strict medical surveillance and in an environment where the necessary medical equipment is available to treat anaphylactic reactions.

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Marie-Noel Primeau, MD
(translation by Andrew Moore, MD FRCPC)

Updated 11/2024

NB : This article is not referring to desensitization or immunotherapy, which is typically prescribed to treat allergies to dust mites, pollens, or wasps, and which is sometimes referred to as "vaccines". This subject is treated in the Respiratory section (Immunotherapy).