Roni Caryn Rabin, New York Times: January 9, 2021
Any site that administers the currently authorized vaccines must be prepared to recognize and treat a severe allergic reaction that may occur, though it is “a rare outcome,” federal health officials said.
Of the nearly 2 million Americans who received coronavirus vaccinations developed by Pfizer and BioNTech during a 10-day stretch last month, 21 experienced a serious and potentially life-threatening allergic reaction called anaphylaxis, federal health officials said Wednesday.
Although the risk is ten times higher than the risk for anaphylaxis after a seasonal flu vaccine, officials described the reaction as “a rare outcome.”
The rate of anaphylaxis following vaccination was estimated to be 11.1 per million doses administered, compared with 1.3 cases of anaphylaxis per million doses of influenza vaccine administered, officials said.
“We know that safety is one of the public’s biggest concerns about the Covid vaccine,” said Dr. Nancy Messonnier, director of the National Center for Immunization and Respiratory Diseases at the Centers for Disease Control and Prevention.
“The anaphylaxis rate may seem high compared to the flu vaccine, but I want to reassure you: This is still a rare outcome.”
Any site that administers the vaccine must be prepared to recognize and treat a severe allergic reaction that may occur, federal health officials said. And though there is less information about reactions to the Moderna vaccine than to the Pfizer-BioNTech vaccine, Dr. Messonnier said, “At this point we really don’t have enough data to say there’s any difference in the risks, so the recommendations apply to both.” Recipients who experience anaphylaxis after receiving the first dose of the vaccine should not receive the second dose, officials said.
Other than the anaphylaxis reactions, which occurred shortly after vaccination, “Our vaccine safety systems haven’t picked up any worrisome signals,” Dr. Messonnier added. “The known and potential benefits of the Covid vaccine outweigh the risk of getting Covid-19.”
The C.D.C.’s analysis of adverse reactions, published on Wednesday, included only those to the Pfizer-BioNTech vaccine administered between Dec. 14 and Dec. 23.
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The vast majority of anaphylaxis reactions — 90 percent — occurred in women, who made up slightly more than half of vaccine recipients. A surprising number of those who went into anaphylaxis — 14 of the 21 — had never experienced an anaphylactic reaction prior to receiving the vaccine, and four had no known allergies at all.
Of the 21 who had reactions, 20 had recovered or been discharged home, and information was lacking on one individual. Nineteen were treated with epinephrine, and four were hospitalized, including three in intensive care. Seventeen were treated in an emergency department.
The C.D.C. said it was still investigating another seven reports of anaphylaxis following the vaccine, which have not been confirmed. The Vaccine Adverse Event Reporting System also identified 83 cases of nonanaphylaxis allergic reactions after the Pfizer-BioNtech vaccination; these people developed symptoms like rash and mild respiratory symptoms within a day of receiving the vaccine.
Among the 21 vaccine recipients who experienced anaphylaxis, 17 were known to have allergies to a variety of triggers, including foods, insects, pets and medications. The median time for anaphylactic reaction was 13 minutes after immunization, but one patient developed the reaction two and a half hours afterward.
Patients with known allergies have been warned to bring an epinephrine injector when they get vaccinated, and providers have been advised to keep patients with allergies for observation for 30 minutes following inoculation.
The new information is disconcerting, said Diana Zuckerman, president of the National Center for Health Research.
“The flaw in the system is that there was a small number of people who had a reaction 30 minutes or later,” she said. “It’s one thing to say everybody should hang around for 15 minutes. But the range was up to 150 minutes, and people aren’t going to hang around that long.”
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