What people with allergies need to know about the COVID-19 vaccine

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The Pfizer-BioNTech COVID-19 vaccine is administered to a personal support worker at The Ottawa Hospital on December 15, 2020, in Ottawa.

Adrian Wyld / The Canadian Press

People with common allergies, such as food, pollen, or pets, are no more likely than the rest of the population to have a rare allergic reaction to the COVID-19 vaccine, experts say.

Two U.S. health workers have had allergic reactions – including a severe reaction – after receiving the Pfizer-BioNTech COVID-19 vaccine this week, CBS News reported Thursday. In Britain, two National Health Services workers had severe allergic reactions after receiving the vaccine earlier this month.

Health Canada has recommended that anyone allergic to any of the ingredients not to receive the vaccine. He also advised anyone who has had a severe allergic reaction to any other vaccine, medicine or food to talk to their healthcare professional first.

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The likelihood of having an allergic reaction to any component of the vaccine, however, is extremely rare, said Tim Vander Leek, president of the Canadian Society of Allergy and Clinical Immunology.

“If anyone thinks they have a reason for not getting a vaccine like the Pfizer vaccine, I think it’s very important that they discuss it with their health care provider, rather than just avoiding it,” did he declare.

What caused the allergic reactions in healthcare workers?

The answer is still unknown. The allergen, or the substance that triggered the allergic reaction, in the two UK cases is still under investigation, according to an email from the UK Medicines and Health Products Regulatory Agency (MHRA).

“One theory is that it may be polyethylene glycol (PEG), but that is not yet proven,” he said.

According to the BBC, both people have a history of severe allergies and both reportedly recovered well the day after receiving the vaccine.

In the cases in the United States, which both occurred at the same hospital in Juneau, Alaska, a male worker presented with puffiness, dizziness and a sore throat within minutes of receiving the vaccine on Wednesday, while that a worker showed signs of an anaphylactic reaction on Tuesday, including an increased heart rate, shortness of breath and a rash, CBS News reported. Both were treated and their reactions were not fatal. The specific allergen has not been reported.

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What is polyethylene glycol

Polyethylene glycol is a compound used in some drugs, cosmetics and foods, the MHRA said. This ingredient has been identified by the National Advisory Committee on Immunization of Canada as a potential allergen in the Pfizer-BioNTech vaccine.

It is not known exactly how many people are allergic to PEG, as these allergies may not always be recognized, but research suggests that it is extremely rare, said Dr Vander Leek. For example, he noted in a review of all the medical literature available between 1977 and 2016, only 37 cases of PEG allergies were reported.

In a statement released Tuesday, the Canadian Society of Allergy and Clinical Immunology said PEG is found in several products that are safely tolerated on a daily basis by many people in Canada.

Like the Pfizer-BioNTech vaccine, the Moderna COVID-19 vaccine, which is expected to receive Health Canada approval soon, also contains PEG, so it is likely that the same recommendations – not to receive this vaccine if people have known allergy to PEG or any ingredient in the vaccine – will apply, said Dr Vander Leek. However, he added, it is important to note that there are many types of PEG molecules and the molecules listed as ingredients in these two vaccines are different. People who are allergic to one type of PEG may be able to tolerate another form of it, he said, stressing that this underscores the importance of seeing a health care provider.

What other ingredients are in the vaccine?

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The medicinal ingredient in Pfizer-BioNTech vaccine is mRNA. In addition to PEG, other non-medical ingredients are: ALC-0315 = ((4-hydroxybutyl) azanediyl) bis (hexane-6,1-diyl) bis (2-hexyldecanoate), 1,2-Distearoyl-sn- glycero -3-phosphocholine, cholesterol, sodium phosphate dibasic dihydrate, potassium phosphate monobasic, potassium chloride, sodium chloride, sucrose and water for injection.

None of these other ingredients have been identified as a likely cause of the allergy, said Dr Vander Leek.

The Pfizer-BioNTech vaccine and some of the COVID-19 vaccine candidates have frequently reported side effects, including fevers and body aches. How do you distinguish an allergic reaction from an expected side effect?

Common responses to vaccines, which can last anywhere from a few days to a week or two, are the result of your immune system activating, said Zainab Abdurrahman, clinical immunologist and allergist and assistant (adjunct) clinical professor of pediatrics at the ‘McMaster University. A rise in body temperature, redness and swelling around the injection site, as well as a general feeling of tiredness or feeling under the weather are all part of the immune system’s response to try to fight and stop it. stop the spread of infection of what he perceives to be a pathogen, said Dr Abdurrahman.

“These are all normal things your body does when it tries to respond to a threat. And we want him to think what you get in the vaccine is a threat, ”so he can recognize and respond to the real pathogen, she said.

An allergic reaction, on the other hand, is not expected and usually occurs within the first minutes to an hour after receiving a vaccine, said Dr Abdurrahman.

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It can involve rashes, breathing problems, swelling, and low blood pressure.

Does being allergic to one substance make you more likely to be allergic to another?

People with asthma, for example, have a higher risk of environmental allergies, Dr Abdurrahman said, but vaccine allergies are extremely rare. The chances of getting anaphylaxis from a vaccine are about one in a million.

“It’s not that much, [for example], having a peanut allergy will increase your risk of having an allergy to the vaccine. we don’t really see that, ”she said.

Although no COVID-19 vaccine has yet been approved for children, trials are underway to test them in adolescents. Are children more sensitive to allergies than adults?

There is no reason to assume that children will be more likely to have allergic reactions to the COVID-19 vaccine, said Dr Abdurrahman.

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Since children typically experience more rash and fever when given other types of vaccines than adults, she says she expects it to be more common for them to have effects. side effects such as localized pain, redness, swelling and high temperature. However, it is not known which vaccine the children could possibly receive.

What are the options for people with known allergies to vaccine ingredients?

They may be able to choose another vaccine that does not contain the component to which they are allergic. when others become available, said Dr Vander Leek. Alternatively, he says, there may be potential ways to desensitize the body so that they can tolerate receiving it.

Although he noted that it is not yet known whether this could apply to the COVID-19 vaccine, desensitization, which involves gradually increasing the dose from an extremely small amount, is used routinely when patients have to take life-saving medications to which they are allergic. .

Initial COVID-19 vaccinations in Canada and around the world raise questions about how people respond to the vaccine, how pregnant women should approach it, and how far away herd immunity can be. Journalist Kelly Grant and science journalist Ivan Semeniuk discuss the responses. The Globe and Mail

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