What do cases of allergic reaction in the UK mean for the Pfizer COVID-19 vaccine?

Explanation: What do the UK allergic reactions mean for the Pfizer vaccine?

US Regulators Expected to Consider Emergency Authorization of Pfizer Vaccine (Representational)


Britain’s drug regulator has advised people with a history of significant allergies not to get the Pfizer-BioNTech COVID-19 vaccine after two people reported adverse reactions on the first day of its launch in the UK. Here are some questions and answers about the cases and what they could mean.

What exactly happened?

UK officials said there have been two reports of anaphylaxis and one report of a possible allergic reaction since the launch began.

Anaphylaxis can cause a sore throat, shortness of breath and difficulty swallowing, according to the American Academy of Allergy, Asthma and Immunology.

Anaphylaxis is an overreaction of the body’s immune system, described by the UK National Health Service as serious and sometimes life-threatening.

Who shouldn’t get the vaccine according to UK regulators?

British regulators initially responded by saying that anyone with a history of a significant allergic reaction to a vaccine, drug or food should not inject themselves.

An adviser to the group later said he was “modifying” the advice in part to say that a food allergy was not a risk. Late on Wednesday, the UK regulator said that anyone with a history of anaphylaxis to a vaccine, drug or food should not receive the vaccine. Pfizer had excluded people with a history of significant adverse reactions to vaccines or its vaccine ingredients from late-stage trials.

How does this affect the prospects for US authorization?

US regulators are expected to consider emergency authorization of the Pfizer vaccine shortly after an advisers meeting Thursday. Moncef Slaoui, who is spearheading the US government’s vaccine development efforts, said on Wednesday that he hoped British allergic reactions would be considered in the US authorization process and that people with known severe allergic reactions they probably shouldn’t take the vaccine until it is better understood.

What do the doctors say?

Some praised the caution of UK regulators, while others said the available evidence did not warrant broad restrictions. “For the general population, this does not mean that they should be anxious to receive the vaccine,” said Stephen Evans, professor of pharmacoepidemiology at the London School of Hygiene and Tropical Medicine. What would be prudent, he said, would be “for anyone who has known a severe allergic reaction who needs to wear an EpiPen to postpone vaccination until the reason for the allergic reaction is clarified.”

Mayo Clinic virologist Gregory Poland, who has advised US regulators, described Britain’s initial reaction as “exaggerated”, pointing to the initial response on food allergies, which he said “has nothing to do with this.”


“I would have said, ‘If you’ve had anaphylactic-level reactions to vaccines, we want to know, so we need to be more careful,'” he said.

“That doesn’t mean I wouldn’t immunize you. But I would do it in a more controlled environment.”

Peter Openshaw, professor of experimental medicine at Imperial College London, praised the way the reactions had been handled.

“The fact that we know so early about these two allergic reactions and that the regulator has acted on them to issue precautionary advice shows that the monitoring system is working well,” he said.

Mitchell Grayson, director of the division of allergy and immunology at Nationwide Children’s Hospital in Ohio, expressed concern about how the issue could reduce interest in vaccines.

“I am concerned that the whole event will make millions of people choose not to get vaccinated because of what they heard,” he said.

How common are severe or major allergies?

In the UK in 2012 there were around seven hospital admissions per 100,000 people for severe allergies.

This included different triggers, such as food, medication and insect bites, “said Louisa James, an immunology expert at Queen Mary University of London.

Deaths remain very rare and have not increased even as hospital admissions have increased in many countries.

(Except for the headline, this story has not been edited by NDTV staff and is posted from a syndicated feed.)