UK health officials have warned that people with a history of “significant” allergic reactions to vaccines, drugs or food should not receive Pfizer’s COVID-19 vaccine. Two people in the UK’s first COVID-19 vaccine group, both health workers, experienced “side effects” after taking it.
So far, only three cases of allergic reactions have been reported in the United States. A few health workers at a hospital in Alaska experienced allergic reactions after taking the vaccine. One worker, who had no history of allergies, had a severe reaction known as anaphylaxis, while the second had a less severe allergic reaction.
A second serious response was reported later this week in a separate hospital in Alaska. All three were treated and quickly recovered.
The Centers for Disease and Control and Prevention recommends that people with a “history of serious allergic reactions such as anaphylaxis to a vaccine or injectable therapy” should take “precautions” but not avoid the vaccine altogether.
Those guidelines are based on Pfizer’s clinical studies, in which about 22,000 people received the vaccine and well under 1% may have had allergic reactions to it. “Among a subgroup of participants in the Phase 2/3 clinical studies, 0.63% of the participants in the vaccinated group had hypersensitivity-related adverse reactions possibly representing allergic reactions (compared to 0.51% in the placebo group),” reads the interim report. of the CDC. Clinical Considerations When Using the Pfizer Vaccine.
During the studies, “there were no cases of anaphylaxis,” Pfizer said. “Overall, no safety signals of concern were identified in our clinical studies, including no sign of serious allergic reactions associated with the vaccine,” a Pfizer spokesperson told CBS News. “However, reports of adverse reactions outside of clinical studies are a very important part of our pharmacovigilance activities and we will review all available information on this case and all reports of adverse reactions following vaccination.”
“We do not yet have full details of the Alaska report on a possible serious allergic reaction, but are actively working with local health authorities to assess this,” said the spokesman. “We will closely monitor all reports indicating serious allergic reactions after vaccination and update the language of the labeling as necessary.”
People who wanted to participate in Pfizer’s Phase 3 study “were excluded if they had a history of serious adverse reactions related to a vaccine and / or a severe allergic reaction (eg, anaphylaxis) to any part of the study vaccine”, the company said. . So it is true that people with a history of severe allergic reactions will use the vaccine for the first time as soon as it is released to the public.
Dr. Mark Dykewicz, an allergy and immunology expert at St. Louis University Hospital and a member of the Food and Drug Administration’s Advisory Committee on Allergenic Products, said he has asked questions about the vaccine from patients with an anaphylactic history.
“I tell my patients to go get it,” he said.
According to Dykewicz, the risk is reduced by the presence of medical personnel at the time of injection, when a reaction is most common. CDC guidelines call on vaccine providers to “observe patients with a history of anaphylaxis (from any cause) for 30 minutes after vaccination … to monitor for the occurrence of immediate side effects” and to observe “all other individuals” “for 15 minutes after vaccination.”
Dykewicz emphasized that the benefit of protection against COVID-19 outweighs the risk of a one in a million chance of a serious allergic reaction to a vaccine. “When weighing the pros and cons of this, I would recommend that they get it,” he said.
Overall, the overall risk of anaphylaxis with vaccines (of all types) is about 1 [in] 1,000,000, “said Dr. David Peden, a pediatric allergy and immunology expert at the University of North Carolina at Chapel Hill Medical School and chair of the allergen product advisory committee.” It does happen, but it is extremely rare, ”he said.
Since allergic reactions to Pfizer’s vaccine have yet to be formally studied, it is not yet known which component or components of the drug can cause a reaction. “It is unclear which element of the vaccine is responsible for the small number of allergic emergencies associated with the vaccine,” said Peden.
According to Dykewicz, the Pfizer vaccine does not contain any of the “common suspects,” such as gelatin, which are known to cause a reaction.
The part of a vaccine that attacks a virus – messenger RNA, in the case of Pfizer and Moderna – is just one component; they also contain small amounts of other ingredients known as excipients. “Stabilizers,” usually sugars or gelatin, are adjuvants, according to the CDC, that help keep the vaccine potent during transport and storage. Pfizer’s vaccine, which is kept 94 degrees below zero Fahrenheit to maintain efficacy does not contain gelatin. It is also free from preservatives.
“Most allergy / immunology doctors are most concerned about the additives to stabilize the vaccine, rather than the actual vaccine antigen,” said Peden.
It is too early to know if similar cases could occur Modern vaccine, which the FDA approved Friday. A representative from Moderna told members of the FDA’s Vaccine Advisory Panel that there was one report of anaphylaxis in studies, but it came more than two months after vaccination and was therefore probably not linked to the vaccine, STAT reports. Moderna’s chief medical officer also noted at the meeting that the vaccine’s lipid nanoparticles – tiny spheres of fatty material used to deliver the mRNA – used in the vaccine are not the same lipid nanoparticles as Pfizer’s.
However, Dykewicz said that without knowing which component of the Pfizer’s vaccine caused the reactions, it’s impossible to know whether Moderna’s vaccine has it in common. “The bottom line is, at this point, we don’t know what the component or components are that trigger an allergic reaction,” he said.
It will take time to focus on the culprit, time that will also help determine how common such reactions are in the general population. Dr. Amal Assa’ad, deputy director of the Allergy and Immunology Division at Cincinnati Children’s Hospital and member of the advisory committee, said without a “denominator” it will be difficult to say whether allergic reactions are occurring at the expected rate. .
And people who have never had allergic reactions may still be at risk for a new substance, including vaccines. Still, experts stress that the risk is very small, and even those with a history of allergic reactions should be immunized.
“The risk, while not zero, is extremely small, and people without any history of anaphylaxis in the vaccine should not avoid vaccination on this basis,” said Peden. “… In general, even with a history of allergy (except for a specific history of anaphylactic reaction to another vaccine), people should continue with COVID-19 immunization, especially if they are in a high-risk group.”