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

UK health authorities warning Pfizer should not be given to anyone with a history of a “serious” allergic reaction to a vaccine, drug, or food. COVID-19 (new coronavirus infection) (# If there is no character limit, add parentheses when it first appears vaccine. Two of the first UK COVID-19 vaccine groups, both healthcare professionals, experienced “side effects” after taking it.

So far, only three cases of allergic reactions have been reported in the United States.Pair of healthcare professionals Alaska hospital I experienced an allergic reaction after vaccination. One worker with no history of allergies had a serious reaction called anaphylaxis, and the second worker had a less serious allergic reaction.

A Second serious reaction It was reported later this week at another hospital in Alaska. All three were processed and recovered quickly.

Centers for Disease Control and Prevention Recommended People who “have a history of severe allergic reactions such as anaphylaxis to vaccines and injections” need to be “prevented” but do not need to avoid the vaccine altogether.

This guidance is based on Pfizer’s clinical trials. In this study, about 22,000 people were vaccinated and less than 1% were likely to have an allergic reaction. “Of the subset of participants in Phase 2/3 clinical trials, 0.63% of participants in the vaccination group had hypersensitivity-related adverse events that could represent an allergic reaction (placebo group). Compared to 0.51% of) “, the CDC reads. Provisional clinical consideration For the use of Pfizer vaccine.

“There were no cases of anaphylaxis,” Pfizer said during the trial. “Overall, there were no signs of safety in clinical trials, including signs of a serious vaccine-related allergic reaction,” a Pfizer spokeswoman told CBS News. “However, reporting adverse events outside of clinical trials is a very important factor for pharmacovigilance activities, and we will review all available information on this case and all reports of adverse events after vaccination. . “

“We don’t yet know all the details of Alaska’s report on the possibility of a serious allergic reaction, but we are actively working with local health authorities to assess it,” a spokesman said. “Carefully monitor all reports suggesting a serious allergic reaction after vaccination and update the display language as needed.”

According to the company, people wishing to participate in Pfizer’s Phase 3 trials have a history of “severe side effects associated with the vaccine and / or a severe allergic reaction (such as anaphylaxis) to any component of the study vaccine. Excluded in some cases. ” .. Therefore, it is true that people with a history of severe allergic reactions will only be vaccinated when they are made public.

Dr. Mark Dykewitz, an allergy and immunology expert at the University Hospital of St. Louis and a member of the Food and Drug Administration Allergen Product Advisory BoardHe said he was answering questions about vaccines from patients with a history of anaphylaxis.

“I’m telling patients that they should be willing to get it,” he said.

According to Dykewicz, having a healthcare professional at the time of injection, where the reaction is most common, reduces the risk. The CDC guidance states that vaccination providers should “observe patients with a history of anaphylaxis (for whatever reason) for 30 minutes after vaccination and monitor the occurrence of immediate side effects” and “everyone else”. I want to observe. “15 minutes after vaccination.”

Dykewicz Benefits of protecting from COVID-19 It outweighs the one-millionth risk of a severe allergic reaction to the vaccine. “When balancing the strengths and weaknesses of this, I encourage them to get it,” he said.

“Overall, the general risk of anaphylaxis for vaccines (of all types) is about 1. [in] “It happens, but it’s very rare,” says Dr. David Peden, a pediatric allergy and immunology expert at the University of North Carolina at Chapel Hill Medical College and chair of the Allergen Products Advisory Board. I did.

Allergic reactions to Pfizer’s vaccine have not yet been formally studied, so it is not yet known which components of the drug can cause the reaction. “It’s unclear which component of the vaccine is responsible for the few vaccine-related allergic emergencies,” Peden said.

According to Dykewicz, Pfizer vaccines do not contain “normal suspects” like gelatin, which are known to cause reactions.

Some of the vaccines that attack the virus (messenger RNA in the case of Pfizer and Moderna) are just one component. They also contain small amounts of other ingredients known as excipients. “Stabilizers”, generally sugar or gelatin, are excipients that help keep the vaccine strong during transportation and storage. According to the CDC..Pfizer vaccines stored in 94 degrees below zero Fahrenheit, which maintains its efficacy, does not contain gelatin. It also contains no preservatives.

“Most allergy / immunology doctors are most worried about the additives that stabilize the vaccine, not the actual vaccine antigens,” Peden said.

It’s too early to know if a similar case could occur Modern vaccine, FDA approved on Friday.The representative of Moderna told the members FDA Vaccine Advisory Board There was one report of anaphylaxis during the study, but it may not have been associated with the vaccine because it was more than two months after vaccination. STAT report.. Modena’s Chief Medical Officer also pointed out during the meeting that the lipid nanoparticles of the vaccine (small spheres of fatty material used to deliver mRNA) are not the same lipid nanoparticles as Pfizer’s.

However, Dykewicz said it would be impossible to know if Moderna’s vaccines have something in common without knowing which component of Pfizer’s vaccine caused the reaction. “The bottom line is that at this point we don’t know what is causing the allergic reaction,” he said.

Focusing on the perpetrator takes time and also helps determine how common such reactions are to the general public. Dr. Amal Asaad, Associate Director and Advisory Board member of the Cincinnati Children’s Hospital’s Department of Allergy and Immunology, would determine if an allergic reaction is occurring at the expected rate without a “denominator”. I said it would be difficult. ..

Also, people who have never had an allergic reaction may be at risk of taking new substances such as vaccines. Still, experts emphasize that the risk is very low, and even people with a history of allergic reactions need to be immunized.

“The risk is not zero, but it is very small and people without a history of vaccine anaphylaxis should not avoid vaccination based on this,” Peden said. “… In general, even if you have a history of allergies (except for a specific history of anaphylactic reactions to another vaccine), you should continue COVID-19 vaccination, especially if you are in a high-risk group. “