Two British people with severe allergies apparently had allergic reactions to Pfizer/BioNTech’s COVID-19 vaccine, raising questions about whether it is safe for people with preexisting allergies.
In response, British regulators advised those with severe allergies to avoid the vaccine.
It was not immediately clear what triggered the allergic reactions. Unlike some vaccines, in the Pfizer/BioNTech vaccine there are no preservatives or egg products, which have been known to trigger reactions with other types of vaccines.
Allergic reactions were not a significant problem in the U.S. trial in which more than 20,000 people have received both two doses of the vaccine, but the U.S. trials kept out subjects who have had severe allergic reactions, said Moncef Slaoui, co-head of Operation Warp Speed – the government program tasked with developing, manufacturing and distributing COVID-19 vaccines.
Slaoui said he assumes that the U.S. Food and Drug Administration committee meeting Thursday will discuss this issue and will suggest that people with severe allergies “should not take the vaccine until we know exactly what happened.”
But a vaccine that triggers dangerous reactions in people with severe allergies poses a major challenge in the U.S., said Dr. Peter Hotez, a pediatrician and dean of the National School of Tropical Medicine at Baylor College of Medicine in Houston.
“If you start issuing recommendations that anyone with an EpiPen doesn’t get vaccinated, that could be a showstopper for Americans,” he said. About 3 to 4 million Americans carry epinephrine with them at all times in case of allergic reactions, Hotez noted, and 50 million have less severe allergies.
Hotez was confused by the allergic reaction, which was not predicted by trials in tens of thousands of people.
“It’s very inconsistent,” he said. “That’s why it’s really puzzling me.”
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In the U.S. trial, there were more allergic reactions in the group that received the vaccine than among placebo recipients, but both represented a fraction of 1% of trial participants.
In a statement Wednesday, Pfizer said that its trials did not include people with a “history of severe adverse reaction associated with a vaccine and/or severe allergic reaction (eg, anaphylaxis) to any component of the study intervention(s).”
The companies are working with British regulators “to fully understand each case and its causes. Pfizer and BioNTech are supporting the MHRA in the investigation,” according to the statement.
Moderna did not immediately respond to a request about whether people with severe allergies were included in their trials.
As more people receive the vaccine, vaccine experts expect other reactions will crop up – both connected to the shot and by coincidence.
British regulators authorized use of the Pfizer/BioNTech vaccine late last month, and the U.S. Food and Drug Administration appears poised to do the same as soon as the end of this week. Thousands of people in the U.K. have received the vaccine since it was first distributed on Tuesday.
Dr. Gregory Poland, who runs the Vaccine Research Group at Mayo Clinic in Minnesota, said he thinks the British regulators over-reacted.
People who have had anaphylactic shock reactions to previous vaccines should avoid this one, he said, but those with reactions to something other than a vaccine should still be allowed to receive the COVID-19 shot for now, said Poland, who studies the immunogenetics of vaccine response in adults and children.
He said he hopes that the FDA committee that is meeting tomorrow to consider the Pfizer/BioNTech vaccine will require the companies to actively study the issue, even after the vaccine is authorized, contacting people who received it, for instance, to ask if they’ve had reactions.
He said he hopes the committee will also require the companies to keep track of any future neurological side effects from the vaccine. Four people in the trials who received the active vaccine developed Bell’s Palsy, a temporary weakness or stiffness in facial muscles, which is worth following, Poland said, but also could have happened purely by chance.
Dr. Paul Offit told CNN early Wednesday that severe allergic reactions to vaccines occur in about one of every 1.4 million shots. That’s why people are asked to stay in a doctor’s office for a few minutes after a vaccination, said Offit, an infectious disease specialist and director of the Vaccine Education Center at Children’s Hospital of Philadelphia.
Rather than a “blanket recommendation” for people with allergies, “the smarter thing to do would be to try and look at these two patients and see what specific component of the vaccine they were allergic to,” he said.
There are immediate treatments for allergic reactions, he noted.
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The two Britons, both of whom work for the National Health Service, have not been identified but are “recovering well,” according to Stephen Powis, the national medical director for the National Health Service in England.
“As is common with new vaccines the MHRA (Medicines and Healthcare products Regulatory Agency) have advised on a precautionary basis that people with a significant history of allergic reactions do not receive this vaccination after two people with a history of significant allergic reactions responded adversely yesterday.” Powis said in an e-mailed statement.
Until yesterday, people who were allergic to ingredients in the vaccine were told to avoid the vaccine, but now, the guidance from the U.K.’s regulatory agency, MHRA, advises that anyone who has had a severe reaction to anything in the past should avoid the vaccine for now.
“We are fully investigating the two reports that have been reported to us as a matter of priority. Once all the information has been reviewed we will communicate updated advice,” an MHRA spokesperson said via email.
“In line with existing advice we advise anyone with a history of a significant allergic reaction due to receive the Pfizer COVID vaccine to speak to your healthcare professional who is administering the vaccine.”
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This article originally appeared on USA TODAY: COVID vaccine allergic reaction: How Pfizer side effect may affect US