Key Takeaways

  • Among Mass General Brigham employees, those with a history of severe allergic reactions reported more symptoms after receiving COVID-19 mRNA vaccines, but these symptoms did not impede completion of the two-dose vaccine series.
  • The findings support the overall safety of mRNA COVID-19 vaccines.

“We hope these data will help inform ongoing conversations with patients who are hesitant to receive COVID-19 vaccination due to allergy concerns.

Kimberly G. Blumenthal, MD, MSc
Co-Director, Clinical Epidemiology Program, Division of Rheumatology, Allergy and Immunology, Massachusetts General Hospital

BOSTON – New research addresses ongoing concerns regarding risks of allergic reactions after receiving mRNA COVID-19 vaccines, particularly for individuals with a history of severe allergic reactions. The JAMA Network Open study of employee vaccinations within the Mass General Brigham health care system revealed that although people with such a history reported more allergic symptoms after vaccination, nearly all of them were able to become fully vaccinated.

In the study of 52,998 health care employees, 474 (0.9%) reported a history of severe allergic reactions to medications, vaccines or allergens. Survey results showed that 11.6% of employees with this history reported allergic reactions after receiving dose 1 or 2 of a COVID-19 mRNA vaccine, compared with 4.7% of employees without this history. High-risk allergy history was associated with a 2.5-times increased relative risk of allergic reactions, with the highest risks for hives and angioedema. However, despite these symptoms, 5,1706 employees (97.6%) received 2 doses of an mRNA COVID-19 vaccine.

“The results of this study can help guide expectations for patients with high-risk allergy histories. Symptoms such as hives and swelling may occur, particularly with the first vaccine dose, but most reported allergic symptoms did not impede completion of the two-dose mRNA vaccine series,” says lead author Lily Li, MD, allergy faculty in the Division of Allergy and Clinical Immunology at Brigham and Women’s Hospital.

The findings provide reassurance regarding the safety of mRNA COVID-19 vaccination in individuals regardless of allergy history. “We hope these data will help inform ongoing conversations with patients who are hesitant to receive COVID-19 vaccination due to allergy concerns,” says senior author author Kimberly G. Blumenthal, MD, MSc, co-director of the Clinical Epidemiology Program within Massachusetts General Hospital’s Division of Rheumatology, Allergy and Immunology. “At our institutions, nearly all individuals with and without a history of high-risk allergy were able to complete the two-dose vaccine series.”

Co-authors include Lacey B. Robinson, MD, MPH; Rajesh Patel, MD, MPH; Adam Landman, MD; Xiaoqing Fu, MS; Erica S. Shenoy, MD, PhD; Dean M. Hashimoto, MD; Aleena Banerji, MD; Paige G. Wickner, MD, MPH; Upeka Samarakoon, MS, PhD, MPH; Christian M. Mancini, BS; and Yuqing Zhang, Dsc.

Funding for the study was provided by the National Institute of Allergy and Infectious Diseases of the National Institutes of Health and by the Massachusetts General Hospital Department of Medicine Transformative Scholar Program.

About the Massachusetts General Hospital
Massachusetts General Hospital, founded in 1811, is the original and largest teaching hospital of Harvard Medical School. The Mass General Research Institute conducts the largest hospital-based research program in the nation, with annual research operations of more than $1 billion and comprises more than 9,500 researchers working across more than 30 institutes, centers and departments. In August 2021, Mass General was named #5 in the U.S. News & World Report list of "America’s Best Hospitals."

About Brigham Health
Brigham Health, a global leader in creating a healthier world, consists of Brigham and Women's Hospital, Brigham and Women’s Faulkner Hospital, the Brigham and Women’s Physicians Organization and many related facilities and programs. With more than 1,000 inpatient beds, approximately 60,000 inpatient stays and 1.7 million outpatient encounters annually, Brigham Health’s 1,200 physicians provide expert care in virtually every medical and surgical specialty to patients locally, regionally and around the world. An international leader in basic, clinical and translational research, Brigham Health has nearly 5,000 scientists, including physician-investigators, renowned biomedical researchers and faculty supported by over $700 million in funding. The Brigham’s medical preeminence dates back to 1832, and now, with 19,000 employees, that rich history is the foundation for its commitment to research, innovation, and community. Boston-based Brigham and Women’s Hospital is a teaching affiliate of Harvard Medical School and dedicated to educating and training the next generation of health care professionals. For more information, resources, and to follow us on social media, please visit