A resident of an EHPAD in the South of France receives a dose of the vaccine against Covid 19, January 18, 2021. -

Frederic DIDES / SIPA

  • Among the side effects of vaccination against Covid-19, one of the most serious is linked to an allergy to a product present in the Pfizer and Moderna vaccine: polyethylene glycol.

  • But only a handful of French people are allergic to this product, which makes it possible to thin drugs, vaccines and cosmetics.

  • The rest of the people - even very - allergic to dust mites, to certain foods or to animals do not need to worry.

If you are allergic to dust mites, pollen or avocado, can you get vaccinated against Covid-19?

This is one of the questions that comes up a lot in recent days, especially in the call for questions that we have made. 

20 Minutes

therefore takes stock of what we know for the moment.

Don't panic: there are many risks after a vaccination, but only for a handful of people allergic to two products in particular.

From clinical trials, the Pfizer laboratory had warned that allergic reactions could take place.

Adverse effects confirmed during real-life deployment, especially in the United Kingdom, the first country to embark on the adventure, where two allergic cases have been reported and where the public health agency has advised against vaccination for certain people with allergies from December 9, 2020.

What are the risks ?

In France, for the moment, there are four cases of severe allergic reaction in nearly 700,000 vaccinated patients.

A level comparable to the risk of allergy to other vaccines and drugs, namely about 1 in 100,000.

In addition, in all cases of allergic reaction, even serious, no death is to be deplored, in France or abroad.

How does it manifest itself?

By skin reactions, a drop in blood pressure or, worse, anaphylactic shock, which can be life threatening.

"The reactions occur immediately, within half an hour," specifies Frédéric de Blay, president of the French Federation of Allergology (FFAL).

There is no more risk with this vaccine than with any other.

And the precautions are the same: we wait a quarter of an hour, a little more if the person is not well.

"

A handful of affected allergic people

In France, around 30% of the population suffers from an allergy.

Fortunately, not all of these people are affected by the risk after Pfizer's vaccine.

Who should beware?

“Only people who are allergic to two vaccine compounds: polyethylene glycol (or Peg) and polysorbate,” explains Marie Lachâtre, infectious disease specialist at the Center for Clinical Investigations in Vaccinology at Cochin Hospital (AP-HP).

These two substances are used to thin the vaccines.

Peg is present in the vaccines of Pfizer and Moderna, the polysorbate in that of Astrazeneca.

Clearly, people who know they are allergic to Peg cannot be vaccinated for the moment and will have to wait for the arrival of other vaccines, without these substances.

Second case of contraindication: If a person develops an allergic reaction for the first time after the first dose of Pfizer or Moderna vaccine, they could not receive the second dose.

What to do if in doubt?

“Patients who have had a severe reaction (asthma attack, anaphylactic shock, diarrhea, etc.) after taking a drug, but who no longer know which one, must do a check-up with an allergist before the vaccine.

But all the others, no!

", Slice Frédéric de Blay, who ensures that" all allergists are harassed by worried patients.

In any case, during the pre-vaccination consultation, the doctor should ask you if you have ever had an allergic reaction to a vaccine or a drug, and if so, which ones?

To reassure, the French Federation of Allergology posted online this week a frequently asked question.

Which reminds you that if you are therefore allergic - even in a severe way - to dust mites, to certain foods, asthmatic because allergic, no problem: you can go to the vaccination centers.

Anyway, in case of doubt, everyone can ask their doctor or the doctor who is vaccinating.

Find our file

A very minor allergen

How can you be sure that you are not allergic to the two substances in vaccines that can cause problems?

"We can do skin tests vis-à-vis the Peg," continues the pulmonologist at Strasbourg University Hospital.

But there's no point in getting tested if you've never had an allergy.

It's looking for a needle in a haystack!

“Especially since Peg is found not only in injectable drugs, but also in cosmetics.

"It is a very unimportant allergen: it is widely used and causes few reactions," continues Frédéric de Blay.

In my CHU, one of the most important centers in allergology, out of 7,000 patients, we must see one or two per year who are allergic to Peg… It is so rare that there is no epidemiological study.

"

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  • Coronavirus

  • Allergy

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  • Vaccine