LESS THAN TWO DOZEN OF the nearly 2 million people who received the first doses of Pfizer's coronavirus vaccine experienced anaphylaxis, a dangerously severe form of allergic reaction. An analysis Wednesday from the Centers for Disease Control and Prevention and Food and Drug Administration showed that from Dec. 14 to 23, there were 21 cases of anaphylaxis after administration of nearly 1.9 million first doses of the Pfizer-BioNTech COVID-19 vaccine. Nearly three-quarters of those reactions – 71% – occurred within 15 minutes of vaccination. Anaphylaxis is a life-threatening allergic reaction that the CDC says can occur after a vaccination, although rarely. It typically occurs within minutes to hours. The 21 cases of anaphylaxis were among 4,393 reports of adverse events following a dose of the Pfizer vaccination, according to the CDC. Among those instances, 175 reports were identified for further review as possible severe allergic reactions. Seventeen of the 21 people who experienced anaphylaxis had documented histories of allergies or allergic reactions, including seven who had a history of anaphylaxis. Among 20 people for which follow-up information was available, all had recovered or had been released home, according to the CDC.
The 21 cases of anaphylaxis translate to a rate of 11.1 cases per 1 million doses. In a briefing on Wednesday, Dr. Nancy Messonnier, director of the CDC's National Center for Immunization and Respiratory Diseases, said the rate of anaphylaxis for flu vaccine is around 1.3 cases per 1 million doses. "I guess you could mathematically say that's 10 times the amount. But I think that misses the point because it's still exceedingly rare," said Messonier, who called the Pfizer vaccine "very safe." The "risk from COVID and poor outcomes from COVID is still more than their risk of a severe outcome from the vaccine." Of the remaining 175 reports of allergic reactions, 86 were deemed nonanaphylaxis allergic reactions, 61 were considered nonallergic adverse events and seven were still under investigation, according to the analysis. The COVID-19 vaccine developed by Pfizer and BioNTech received emergency use authorization in the U.S. last month and has been deemed 95% effective in preventing COVID-19, which has infected more than 21 million people in the country and killed more than 359,000. Many top politicians have publicly received the vaccine to instill public confidence in it, including Vice President Mike Pence and Vice President-elect Joe Biden. The CDC analysis states that mortality from COVID-19 in populations at high risk is "substantial, and treatment options are limited. Widespread vaccination against COVID-19 with highly effective vaccines represents an important tool in efforts to control the pandemic."
Original Findings published by the CDC in MMWR (Jan. 6, 2021):