COVID-19 & Allergic Disease

In light of the COVID-19 pandemic, the BelSACI wants to contribute in providing correct information for those patients with allergic and immunologic diseases. Below you will find educational material from our partners within different societies and research fora.

Statement of the BelSACI

on possible allergic reactions to COVID-19 vaccines

In line with the European Academy for Allergy and Clinical Immunology (EAACI) and the Center for Disease Control (CDC), the Belgian Society of Allergy and Clinical Immunology (BelSACI) wishes to provide the necessary indications to caregivers and patients regarding the risk of reaction allergic in case of administration of the vaccine against COVID-19.

Severe hypersensitivity or allergy reactions (anaphylaxis) following vaccination are rare, estimated at around 1 case per million1. In the two main studies that evaluated the effect of RNA vaccines against COVID-192,4, the same number of possible allergic reactions were observed in the treated groups and the placebo groups: the events related to hypersensitivity concerned 0.63% and 1.5% of patients who received Pfizer-BioNTech and Moderna vaccines, respectively, compared to 0.51% and 1.1% of patients in placebo groups in the same studies. Additionally, the Food and Drug Administration (FDA) identified a weak signal suggesting more cases of hypersensitivity reactions in the vaccine group3,5, but none of these reactions were severe or required the administration of adrenaline. Note that patients with documented allergies to one of the vaccine components were excluded from the studies.

Real-life immunization data were recently released by the CDC6: Out of nearly 2 million doses of Pfizer-BioNTech vaccine administered in the United States, 175 cases of possible allergic reaction have been reported. However, only 21 severe allergic reactions (anaphylaxis) have been documented, for a rate of 11 cases per million doses. Of these 21 cases, 17 occurred in people with a prior documented history of allergic reactions, of which 7 had previously experienced anaphylactic reactions in other circumstances. The median time between injection and reaction was 13 minutes and the majority (86%) of reactions occurred within 30 minutes. The 20 patients for whom information is available have all made a full recovery. Regarding the reactions considered as non-anaphylactic, 86 were probable allergic non-anaphylactic reactions and 61 were non-allergic side effects (extensive local reaction, malaise etc.). It should be noted that at this stage we do not have such complete data for the Moderna vaccine.

Hypersensitivity reactions to vaccines are usually caused by an inactive ingredient or excipient. The vaccines from Pfizer-BioNTech and Moderna do not contain any food allergens, drugs or latex, or any component that may interact with hymenoptera venoms, but both contain polyethylene glycol (PEG) 7,8. The AstraZeneca and Johnson & Johnson vaccines currently in development do not contain PEG but do contain polysorbate 80. Allergies to PEG are extremely rare9 but to date constitute a formal contraindication to the administration of the Pfizer-BioNTech and Moderna vaccines10,11.

A person presenting a severe reaction (generalized hives, malaise, abdominal pain, respiratory distress, cardio-respiratory arrest) during the injection of a first dose of the vaccine should be evaluated by a specialist before possible administration of the second dose. Testing for serum tryptase one hour and four hours after the reaction should help determine if this is indeed anaphylaxis. You must also pay attention to other allergens present during the procedure (disinfectants, gloves and latex syringe plungers, etc.). Local reactions (swelling, redness) and symptoms of slight fatigue, stiffness, or fever are possible after any vaccination and should under no circumstances be considered as allergic reactions.

We stress that the benefit of an effective vaccine against COVID-19 far outweighs the risk of a severe allergic reaction. The risk of anaphylaxis exists with all medicines, including vaccines, but is low enough in view of the expected benefits.

Therefore, we make the following recommendations:

  1. Patients with documented polyethylene glycol (PEG) allergy should not receive Pfizer-BioNTech or Moderna vaccine at this time. We remind that allergy to PEG is extremely rare.

  2. Patients who have previously experienced a severe allergic reaction (anaphylaxis) when injecting a vaccine should consult their allergist to determine their individual risk if the vaccine is administered.

  3. There is no contraindication to the vaccine against COVID-19 in patients with allergies, even severe ones, to food (including gelatin and eggs), to latex, to hymenoptera venoms, to pollens. or other aeroallergens.

  4. As with any vaccine, each patient receiving the vaccine should be monitored for 15 minutes. For people who have previously experienced severe reactions when injecting vaccines, a 30-minute monitoring is recommended. The same time is recommended for patients with mast cell disease or severe asthma.

  5. Each vaccination site should be equipped to deal with a possible allergic reaction. The presence of a person able to manage allergic reactions is necessary. The use of latex-free material is recommended.

  6. In the event of a severe immediate reaction, it is recommended to administer the appropriate treatment (oxygen, adrenaline, etc.), to take a tube of blood 1 hour and 4 hours after the injection to measure serum tryptase and refer the patient to an allergic specialist, especially if a second dose is to be administered.


This statement will be regularly updated based on available data and the arrival of other vaccines on the market.





  1. McNeil MM and DeStefano F. Vaccine-associated hypersensitivity. J Allergy Clin Immunol, 2018.

  2. Polack et al. Safety and Efficacy of the BNT162b2 mRNA Covid-19 Vaccine. N Engl J Med 2020

  3. Pfizer-BioNTech COVID-19 vaccine (BNT162, PF-07302048) [FDA Briefing Document]. Silver Spring, MD: United States Food and Drug Administration, Vaccines and Related Biological Products Advisory Committee; 2020. Available at:

  4. Baden et al. Efficacy and Safety of the mRNA-1273 SARS-Cov-2 Vaccine. N Engl J Med 2020.

  5.  Moderna COVID-19 vaccine [FDA briefing document]. Silver Spring, MD: United States Food and Drug Administration, Vaccines and Related Biological Products Advisory Committee; 2020. Available at:

  6.  Center for Disease Control (CDC) Morbidity and Mortality Weekly Report (MMWR). Allergic Reactions Including Anaphylaxis After Receipt of the First Dose of Pfizer-BioNTech COVID-19 Vaccine — United States, December 14–23, 2020

  7.  Garvey LH and Nasser S. Anaphylaxis to the first COVID-19 vaccines: is polyethylene glycol (PEG) the culprit? British Journal of Anaesthesia 2020.

  8.  Castels M and Phillips E.J. Maintaining Safety with SARS-Cov-2 Vaccines. NEJM 2020.

  9. Wenande E, Garvey LH. Immediate-type hypersensitivity to polyethylene glycols: a review. Clin Exp Allergy 2016.

  10. Klimek L et al. ARIA-EAACI statement on severe allergic reactions to COVID-19 vaccines – an EAACI-ARIA Position Paper.

  11. Sokolowska M. EAACI statement on the diagnosis, management and prevention of severe allergic reactions to COVID‐19 vaccines. Allergy 2021.

CDC guidelines on COVID-19 Vaccines and Allergic Reactions

French guideline on COVID-19 Vaccines and Allergic Reactions

EMA Product Leaflet Pfizer-BioNTech COVID-19 Vaccin.

EMA information on Pfizer-BioNTech COVID-19 Vaccin.

EMA Product Leaflet Moderna COVID-19 Vaccin.

EMA information on Moderna COVID-19 Vaccin.



Other useful information on COVID-19 and allergic disease

The European Academy of Allergy and Clinical Immunolgy (EAACI) has provided a resource centre some of the most useful and recent insights on COVID-19.

Schermafbeelding 2020-05-03 om 15.07.36.

EUFOREA statement from Prof. Peter Hellings with several videos on different topics including the treatment considerations in AIT and biologicals.


Schermafbeelding 2020-05-03 om 15.17.48.