What is the risk of allergic reaction to COVID-19 vaccines?


British health officials have warned that Pfizer’s COVID-19 vaccine should not be given to people with a history of “significant” allergic reactions to vaccines, medication or food. In the first UK COVID-19 vaccine group, two people, both health care workers, experienced “adverse reactions” after taking it.

So far, there have been only three reported cases of allergy in the United States. A pair of health care workers at a hospital in Alaska experienced allergies after taking the vaccine. One worker, who had no previous history of allergy, had a severe reaction, known as anaphylaxis, while another had a less severe allergic reaction.

a Second serious reaction This weekend was reported at a different hospital in Alaska. All three were treated and recovered rapidly.

The Centers for Disease and Control and Prevention recommend that people with a “history of severe allergic reaction such as anaphylaxis to any vaccine or any injection therapy” should take “precaution”, but do not need to avoid the vaccine altogether .

This guidance is based on a clinical trial of Pfizer, in which approximately 22,000 people received the vaccine and less than 1% were likely to be allergic to it. The CDC’s interim reads, “Among a subset of participants in Phase 2/3 clinical trials, 0.63% of participants in the vaccination group had hypersensitivity-related adverse events, possibly compared to allergic reactions (0.51% ). Clinical Considerations for the Use of the Pfizer Vaccine.

During the tests, “there were no cases of anaphylaxis,” Pfizer said. “Overall, there were no safety signs of concern in our clinical trials, with no signs of severe allergic reactions associated with the vaccine,” a Pfizer spokesperson told CBS News. “However, the report of adverse events outside of clinical studies is a very important component to our pharmacovigilance activities and we will review all available information on this case and all reports of adverse events after vaccination.”

“We do not yet have all the details of the report from Alaska regarding a potentially serious allergic reaction, but are actively working with local health officials to assess it,” the spokesperson said. “We will closely monitor all reports indicating serious allergic reactions following vaccination and updated labeling language if necessary.”

Those who wanted to participate in the Phase III trial of Pfizer, “were excluded if they had a history of any component of the vaccine on any of the probes associated with the vaccine and / or severe allergic reaction (eg, anaphylaxis). , “According to the company. So it is true that people with a history of severe allergic reactions are going to take the vaccine for the first time since it has been released to the public.

An allergy and immunology specialist at St. Louis University Hospital and a member of the Allergenic Products Advisory Committee of the Food and Drug Administration, Drs. Mark Diewicz said he is asking patients with anaphylactic history questions about the vaccine.

“I’m telling my patients to go ahead and get it,” he said.

According to Diekiewicz, the risk is reduced by the presence of medical personnel at the time of injection, when a reaction is most common. The CDC Guidance for Immunization calls “to observe patients with a history of anaphylaxis (for any reason) after 30 minutes of vaccination … to monitor for the occurrence of immediate adverse reactions,” and “all Other Persons “to be observed. “15 minutes after vaccination.”

Dykewicz emphasized that COVID-19 Avoidance Benefits There is a one-in-a-million risk of a severe allergic reaction to the vaccine. “In balancing the pros and cons of this I would recommend that they achieve this,” he said.

“Overall, the general risk of anaphylaxis to vaccines (of all types) is about 1 [in] 1,000,000, “according to Dr. David Peden, a pediatric allergy and immunologist specialist at the University of North Carolina at Chapel Hill Medical School and chair of the Advisory Committee for Allergenic Products.” It happens, but is extremely rare, ”he said.

Since the allergic reaction to Pfizer’s vaccine remains to be formally studied, it is not yet known what components, or components, of the drug may react. “It is unclear which element of the vaccine is responsible for the small number of vaccine-associated allergic emergencies,” Peden said.

According to Dykevicz, the Pfizer vaccine does not contain any of the “common suspects” like gelatin, which is believed to be the cause of the reaction.

The part of the vaccine that attacks the virus – in the case of messenger RNA, Pfizer and Modern – has only one component; They also contain small amounts of other ingredients, known as superior. “Stabilizers,” typically sugars or gelatin, are excipients that, according to the CDC, help to keep the vaccine potent during transport and storage. Pfizer vaccine 94 degrees below zero To maintain efficacy, gelatin is not included in Fahrenheit. It is also preservative free.

“Most allergy / immunologist practitioners worry most about additives to stabilize the vaccine rather than the actual vaccine antigen,” Peden said.

It is too early to know if similar cases can come up. Modern commentary, Which the FDA authorized on Friday. A representative from Modern told the members FDA Vaccine Advisory Panel There was a report of anaphylaxis during the trial, but it came more than two months after vaccination and was therefore probably not associated with the vaccine, STAT report. The Modern Chief Medical Officer also noted during the meeting that the vaccine’s lipid nanoparticles – small shells of fatty substances used to deliver mRNA – do not contain lipid nanoparticles in its vaccine that are similar to Pfizer’s. .

Diekiewicz, however, said that without knowing which component of the Pfizer vaccine caused the reactions, it is impossible to know if this is common in Modern’s vaccine. “The bottom line is at this point we don’t know the ingredient or components leading to an allergic reaction,” he said.

Zeroing on the culprit will take time, time will also help determine how common such reactions are in the general population. The Associate Director of the Department of Allergy and Immunology at Cincinnati Children’s Hospital and a member of the Advisory Committee, Drs. Amal Asad said that without “har” it would be difficult to tell if an allergy is occurring at the anticipated rate. .

And people who have never had an allergic reaction may still be at risk with any new substance, including vaccines. Nevertheless, experts insist that the risk is very low, and even those who have a history of allergy should be vaccinated.

“The risk, while not zero, is very small, and people with no vaccine anaphylaxis history should avoid vaccination on this basis,” Peden said. “… In general, even with a history of allergy (except for a specific history of anaphylactic reaction to another vaccine), people should proceed with COVID-19 vaccination, especially if they have a Are in the high-risk group. “

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