Acute allergic reactions occurred at 2.10%, but only 0.025% of employees of two Boston hospitals who received anaphylaxis received their first dose of Pfizer-BioNTech or Moderna COVID-19 vaccine, according to a research letter released yesterday in JAMA.
Scientists from Massachusetts General Hospital and Brigham and Women’s Hospital provided email, text, phone and smartphone app links to 64,900 employees who received one dose of one of the two mRNA coronavirus vaccines from 16 December 2020 to 12 February 2021.
mRNA vaccines “teach” human cells to form a harmless portion of the SARS-CoV-2 protein to elicit an immune response to the virus. The authors noted that people with a history of life-threatening reactions, or anaphylaxis, to allergens such as those in a vaccine, are often reluctant to receive vaccines, which can complicate efforts to end the pandemic.
A total of 25,929 employees (40%) received the Pfizer vaccine, while 38,971 (60%) received the Moderna vaccine. Eighty percent returned at least one symptom survey, which was sent every day for 3 days after vaccination.
Among all vaccinated employees, 1 365 (2.10%) reported acute allergic reactions, which are defined in the survey as itching, rash, hives, swelling and / or breathing symptoms. More Modern vaccines (2.20%) reported symptoms than Pfizer vaccines (1.95%).
Previous anaphylactic episodes
A review of medical records identified anaphylaxis in 16 workers (0.025%) (9 [0.023%] with the Moderna vaccine and 7 [0.027%] with the Pfizer vaccine). The mean age of vaccinees diagnosed as anaphylaxis was 41 years, 94% were women, 63% had a history of allergy and 31% had previously had anaphylaxis.
The mean time from vaccination to anaphylaxis was 17 minutes. One patient required intensive care, 56% received intramuscular epinephrine (to facilitate breathing), and all recovered without experiencing shock or endotracheal intubation. Three workers with a history of anaphylaxis did not receive medical care. The mechanism of anaphylaxis occurrence in the study is unknown.
The Centers for Disease Control and Prevention has previously reported an incidence of anaphylaxis of 2.5 to 11.1 per million doses, most of which are in people with a history of allergies, the authors said.
“The incidence of confirmed anaphylaxis in this study is greater than reported by the Centers for Disease Control and Prevention, based on passive spontaneous reporting methods,” they wrote. “However, the overall risk of anaphylaxis for an mRNA COVID-19 vaccine remains extremely low and is largely comparable to other general healthcare exposures.”
While most vaccinated with anaphylaxis had a history of allergy, the researchers noted that because about 5% of American adults had severe food allergies, and 1% had severe drug allergies, the study group studied had to include nearly 4,000 workers undergoing anaphylaxis. . vaccinated without related adverse events
“In this prospective group of health workers, 98% had no symptoms of an allergic reaction after receiving an mRNA COVID-19 vaccine,” the authors wrote.