What people with allergies should know about Covid vaccines

On Wednesday, two health workers in Alaska also had reactions. One was too easy to be considered anaphylaxis. The other, which occurred in a middle-aged woman with no history of allergies, was severe enough to warrant hospitalization, even after receiving an epinephrine injection.

“What is happening seems really unusual to me,” said Dr. Kimberly Blumenthal, an allergist, immunologist and drug allergy researcher at Massachusetts General Hospital. Vaccine-related allergic reactions are usually rare, occurring at a rate of about one million.

Dr. Blumenthal also pointed out that it is a bit bizarre to see allergic reactions that cluster in just two locations: the UK and Alaska. Zeroing over the commonalities between the two hotspots, she said, could help researchers discover the source of the problem.

The British and American agencies are investigating the cases, but no official has stated a direct link.

But Dr. Blumenthal suspects they were connected to the photos because the reactions were immediate, appearing within minutes of the injection.

“We have to believe she was tied up because of the schedule,” she said.

It is not even known if a certain ingredient could have been the cause. The Pfizer vaccine contains only 10 ingredients. The most important is a molecule called messenger RNA or mRNA – genetic material that can instruct human cells to produce a coronavirus protein called a peak. Once manufactured, Spike teaches the immune system to recognize the coronavirus so that it can be fought in the future. Messenger RNA, which is found naturally in human cells, is unlikely to pose a threat and degrades within about a day of injection.

The other nine ingredients are a mixture of salts, fats and sugars that stabilize the vaccine. None is a common allergen. The only chemical with a history of allergic reactions is polyethylene glycol or PEG, which helps pack mRNA into an oily sheath, protecting it as it enters human cells.

But PEG is generally inert and widespread. It is found in ultrasound gel, laxatives such as Miralax and injectable steroids, among other drugs and products, said Dr. Blumenthal. Despite the ubiquity of the chemical, she said: “I’ve only seen one case of PEG allergy – it’s very, very unusual.”