MHRA issues anaphylaxis warning for Pfizer BioNTech vaccine

The Medicines and Healthcare Products Regulatory Agency (MHRA), Britain’s drug regulator said anyone with a history of anaphylaxis to medicine or food should not get the Pfizer-BioNTech COVID-19 vaccine, giving fuller guidance on an earlier allergy warning about the shot.

Starting with the elderly and frontline workers, Britain began mass vaccinating its population on Tuesday.

The MHRA said there had been two reports of anaphylaxis and one report of a possible allergic reaction since the rollout began.

“Any person with a history of anaphylaxis to a vaccine, medicine or food should not receive the Pfizer BioNTech vaccine,” June Raine, MHRA Chief Executive said in a statement.

Anaphylaxis is an overreaction of the body’s immune system, which the National Health Service describes as severe and sometimes life-threatening.

The fuller guidance, clarifying that the main risk was from anaphylaxis specifically, was issued after consulting experts on allergies. The MHRA had initially advised anyone with a history of a “significant allergic reaction” not to take the shot.

Pfizer and BioNTech said they were supporting the MHRA’s investigation.

Raine told lawmakers such allergic reactions had not been a feature of the Pfizer’s clinical trials.

Pfizer has said people with a history of severe adverse allergic reactions to vaccines or the candidate’s ingredients were excluded from their late-stage trials, which is reflected in the MHRA’s emergency approval protocol.

However, the allergic reactions may have been caused by a component of Pfizer’s vaccine called polyethylene glycol, or PEG, which helps stabilise the shot and is not in other types of vaccines.

Imperial College London’s Paul Turner, an expert in allergy and immunology, who has been advising the MHRA on their revised guidance, told Reuters, “As we’ve had more information through, the initial concern that maybe it affects everyone with allergies is not true.”

“The ingredients like PEG which we think might be responsible for the reactions are not related to things which can cause food allergy. Likewise, people with a known allergy to just one medicine should not be at risk,” Turner told Reuters.