Britain’s medicine regulator has said that anyone with a history of anaphylaxis to any medicine or food should not get the Pfizer-BioNTech COVID-19 vaccine.
Britain began mass vaccinating its population on Tuesday, starting with the elderly and frontline workers.
The Medicines and Healthcare Products Regulatory Agency (MHRA) said there were two reports of anaphylaxis, and one reported a possible allergic reaction since the vaccine rollout began.
“Any person with a history of anaphylaxis to a vaccine, medicine, or food should not receive the Pfizer BioNTech vaccine,” MHRA Chief Executive June Raine said in a statement.
“Most people will not get anaphylaxis, and the benefits in protecting people against COVID-19 outweigh the risks… You can be completely confident that this vaccine has met the MHRA’s robust standards of safety, quality, and effectiveness.”
Anaphylaxis is an overreaction of the body’s immune system, which, according to the National Health Service, is severe and sometimes life-threatening.
Pfizer and BioNTech said they were supporting the MHRA’s investigation.
Britain’s MHRA was the first in the world to approve the vaccine, which was developed by Germany’s BioNTech and Prizer.
MHRA chief Raine told lawmakers that allergic reactions were not seen in Pfizer’s clinical trials.
Pfizer said that people with a history of severe allergic reactions to vaccines were excluded from their late-stage trials, reflected in the MHRA’s emergency approval protocol.
The allergic reactions could have been caused by a component of Pfizer’s vaccine called polyethylene glycol, or PEG, which helps stabilize the shot and is not in other types of vaccines.
Imperial College London’s Paul Turner is an expert in allergy and immunology who has been advising the MHRA on their revised guidance. He 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 that we think might be responsible for the reactions are not related to things that can cause food allergy. Likewise, people with a known allergy to just one medicine should not be at risk,” Turner told Reuters.
The EMA said in an email that all quality, safety, and efficacy data would be taken into account in assessing the vaccine, including data generated outside the EU.
Meanwhile, on Tuesday in the United States, the FDA released documents to prepare an advisory committee meeting on Thursday. According to the FDA, the Pfizer vaccine’s efficacy and safety data met its expectations for authorization.