Updated Dec. 30 – With the U.S. emergency approval late Dec. 13 of the Pfizer-BioNTech coronavirus vaccine, the rollout of the protective shot got swiftly underway on Dec. 14. (See also the latest news in our FAQ.)
The emergency use authorization for giving the vaccine to those age 16 and older sets the stage for millions of Americans – starting with healthcare workers and vulnerable seniors – to be vaccinated in the weeks ahead. The FDA’s emergency approval of the mRNA-based vaccine approval is already being hailed as a potential turning point in a pandemic that has claimed the lives of almost 300,000 Americans.
But what about recent allergy concerns? The FDA says the Pfizer vaccine’s prescribing information will include a highly specific allergy warning – not a sweeping advisory such as the U.K. imposed on Dec. 9. After two British healthcare workers experienced anaphylaxis-like symptoms, the U.K.’s medicines regulatory agency issued a blanket warning that people with a history of anaphylaxis to vaccines, food or drugs should not get the Pfizer vaccine. (The U.K. warning has since been revised, so that only those with known allergies to an mRNA vaccine component are advised not to have the shot.)
Leading U.S. allergists and vaccine experts contended the U.K. allergy advisory went too far. They told Allergic Living that warning will fuel unnecessary doubts.
On Dec. 10, Marion Gruber, director of the FDA’s Office of Vaccines Research and Review, told a panel of experts reviewing the Pfizer-BioNTech vaccine’s clinical trial results that the FDA is in communication with U.K. authorities about the cases of two healthcare workers who experienced reactions.
For the U.S. rollout, she said the FDA and Pfizer have agreed on prescribing information and fact sheets that say “this vaccine should not be administered to individuals with known history of severe allergic reactions to any of component of Pfizer’s COVID-19 vaccine.” As well, Gruber said availability of emergency treatment for anaphylaxis will be required when administering the vaccine – which is standard practice with vaccinations.
What’s Known of U.K. Reactions
The panel of experts voted to recommend emergency use authorization (or EUA) for the Pfizer-BioNTech vaccine, and the FDA then did give approval on Dec. 11. Then on Dec. 12, a panel reviewing for the Centers for Disease Control and Prevention (CDC) also voted in favor of an EUA. CDC director Dr. Robert Redfield then gave the final authorization for the Pfizer vaccine EUA on Dec. 13, allowing the rollout to begin.
The Pfizer vaccine proved to be 95 percent effective in final stage results of a clinical trial that involved 44,000 participants. The safety profile among this large group was also convincing, which is what makes the two British cases unusual. On Dec. 10, during the FDA panel’s review of the safety data on the mRNA-based vaccine, a Pfizer official provided new details about the two Britons who experienced anaphylaxis-like symptoms.
The two women are in their forties. One has food allergies and reported in past having anaphylaxis that required epinephrine. The second has a history of an allergic reaction to one or more medications, “although we don’t know which drugs yet,” said Patrick Caubel, the head of safety at Pfizer. The second woman experienced shortness of breath but her reaction was “more minor,” he said. Both women were treated with epinephrine and recovered.
The FDA completed an independent analysis of Pfizer’s clinical trial results, and found a few instances of what could potentially have been minor allergic reactions among trial participants. “None of these were considered to be serious,” Gruber told the panel. “None of them received epinephrine injections.”
Contrary to rumors on social media, the FDA experts panel was told that people with a history of serious food or medication allergies were not excluded from the vaccine’s Phase 3 trial. Only those who had a past severe adverse reaction to any vaccine or to a component of this vaccine were excluded, said Pfizer’s Dr. William Gruber, senior vice president of vaccine clinical research and development.
“During the course of the trial, we have not see anything that alerted us to a safety signal associated with the vaccine and the potential for anaphylaxis,” he said.
U.S. allergists and vaccine experts are speaking out about the need for clear and consistent guidance, especially at a time when vaccine hesitancy is high.
Dr. Paul Offit, one of the experts on the FDA panel, expressed frustration with the messaging from the U.K. and Operation Warp Speed Chief Advisor Moncef Slaoui regarding allergies and the vaccine. On Dec. 9, Slaoui said he expected U.S. experts would also advise people who have had severe allergic reactions to avoid the vaccine until the cases in Britain were fully investigated.
“There are tens of millions of people in this country who carry EpiPens with them because they have peanut allergies, because they have egg allergies, who are going to believe now that they can’t get this vaccine. That is a lot of people,” says Offit, an advisory committee member and a vaccine expert at the Children’s Hospital of Philadelphia.
Offit recommended the U.S. conduct a smaller study of the vaccine in people with food allergies, in order to put the food allergy issue to rest. “This issue is not going to die until we have better data,” he says.
Reassuring Allergy Patients
As word about the U.K. allergy warning spread through the allergy community, allergists are seeking to reassure their patients about the safety of the vaccine.
“There is no reason to think people with a history of food or drug allergies are at higher risk of a reaction. No reason whatsoever,” says Dr. James Baker, a vaccine expert and founding director of the Mary H. Weiser Food Allergy Center at University of Michigan.
Dr. Kimberly Blumenthal, an allergist and drug allergy expert at Massachusetts General Hospital, called the U.K. advisory potentially “misleading and harmful.” “My concern is that it’s going to lead to unnecessary doubt and fear,” she says. “It’s going to be hard for us to come back from this.”
Massachusetts General is making final preparations to vaccinate tens of thousands of their healthcare workers in the coming days, and there are currently no plans to exclude people with a history of food or drug allergies, says Blumenthal, the hospital’s quality and safety officer for allergy.
If people have had a severe reaction to a vaccine in the past, she will encourage them to consult their allergist before getting the vaccine, or perhaps be monitored for a longer period after receiving the vaccine. But even a reaction to a vaccine in the past wouldn’t necessarily make someone more likely to react to the new vaccine.
“Allergy is an antigen-specific process,” Blumenthal reminds. “Allergy to food doesn’t mean you are allergic to drugs. Allergy to drugs doesn’t mean you are allergic to vaccines.”
Potential Symptom Causes
With few specifics, U.S. experts say they don’t know exactly what happened in the U.K. Anaphylactic reactions to vaccines can occur but are rare – about 1 in 1 million, according to the CDC. When people do react, it is to a specific component in the vaccine, Baker says. In reviewing the ingredients of the Pfizer vaccine, he says: “there are no cross-reacting components to this.”
There has been speculation that polyethylene glycol (PEG), a component of the vaccine, could have been the culprit. While not impossible, the allergy is exceedingly rare, says Blumenthal. The FDA receives from two to eight reports of a suspected PEG allergy annually. “I’ve seen one case PEG allergy.” She says most allergists “have seen zero cases.”
There are other potential responses to a vaccine that have nothing to do with IgE-mediated reactions, the most common form of allergic reactions. For instance, high stress can trigger a vasovagal response, which can have symptoms in common with anaphylaxis, such as flushing, a change in heart rate and a drop in blood pressure. This response can be mistaken for anaphylaxis, the experts say.
Baker urged the allergy community not to be spooked by the U.K. reports. “I am getting this vaccine as soon as I can. I have patients with immune deficiencies that I’m having get this vaccine.”
Blumenthal has similar advice. “Our country needs as many people who are eligible for this vaccine to get it.”
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