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Data Reveal Risks of COVID-19 mRNA Vaccine Allergic Reactions

In This Article

  • After the first mRNA-based COVID-19 vaccines were authorized for emergency use, reports of anaphylaxis caused some doubt about the safety of the vaccines
  • A team of researchers at Mass General Brigham now reports that the risk of life-threatening allergic reaction to the vaccines is low and comparable to the same risks associated with common antibiotics
  • Kimberly Blumenthal, MD, MSc, lead on the study, said that the vaccines have remarkable safety and efficacy across all populations, especially given that they are the first of their kind

Early reports of anaphylaxis—a life-threatening whole-body allergic reaction—associated with the first mRNA-based COVID-19 vaccines caused widespread concern about the safety of the vaccines. Now, a team of researchers at Mass General Brigham reports that the risk of anaphylaxis with the vaccines, although slightly higher than estimated by the CDC, is low. Their findings are published in the Journal of the American Medical Association.

Kimberly Blumenthal, MD, MSc, co-director of the Clinical Epidemiology Program in Division of Rheumatology, Allergy and Immunology at Massachusetts General Hospital, and colleagues surveyed 52,805 Mass General Brigham employees after they received their first dose of an mRNA COVID-19 vaccine. Among the cohort, which included an estimated 4,000 individuals with significant allergies to foods and medications, 2% of vaccine recipients experienced allergic reactions, and anaphylaxis occurred at a rate of 2.47 per 10,000 individuals. This rate was largely comparable to anaphylactic reactions from common antibiotics, said Dr. Blumenthal.

The researchers noted that although the incidence of anaphylaxis was higher than that estimated by the CDC—which put the rate at 0.025 to 0.11 per 10,000 vaccinations—it is still exceedingly low, providing reassurances for patients with a history of food or drug allergies.

Paige Wickner, MD, MPH, medical director of the Department of Quality and Safety at Brigham and Women's Hospital, said that the only allergy exclusion for vaccination was a prior episode of anaphylaxis to an inactive ingredient in the vaccine, called polyethylene glycol, or a cross-reactive inactive ingredient called polysorbate. Additionally, all patients who experienced anaphylaxis following a vaccine recovered, with no incidence of anaphylactic shock or need for a breathing tube.

of mRNA-based COVID-19 vaccine recipients experienced allergic reactions

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