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Reported anaphylaxis in the United States after vaccination, 1990–2016

Published online: January 14, 2019

Anaphylaxis is a rare hypersensitivity reaction that affects multiple organ systems, and occurs when exposure to a trigger leads to a massive release of histamine, tryptase, and other chemicals throughout the body. A variety of signs and symptoms can result, including hives, swelling of the airway, and vomiting. In severe cases, anaphylaxis can be life-threatening. Anaphylaxis reported after vaccination in the United States is rare, with an estimated 1.3 cases per million doses of vaccine administered. Such cases frequently have a history of hypersensitivity or anaphylaxis.

The Vaccine Adverse Event Reporting System (VAERS) is the national surveillance system for reporting adverse health events following vaccination. In a recently published article in The Journal of Allergy and Clinical Immunology (JACI), John R. Su et al. analyzed reports received by VAERS during 1990 through 2016 that described anaphylaxis. The authors initially identified reports in the VAERS database using coding terms assigned to reports from the Medical Dictionary for Regulatory Activities. Then they described case reports that either 1.) met the standardized case definition for anaphylaxis developed by the Brighton Collaboration, or 2.) were diagnosed as anaphylaxis by a physician. Reports were evaluated by patient age, sex, medical history, signs and symptoms, and vaccines administered.

VAERS received 467,960 total reports during 1990 through 2016. Automated searches identified 15,404 potential reports for analysis; a more specific keyword search reduced this count to 2,317 potential reports for analysis. Of these 2,317 reports, 828 met the Brighton Collaboration case definition or were diagnosed as anaphylaxis by a physician. Of 478 reports in children aged <19 years, 65% were male, and childhood vaccines (e.g., combined measles, mumps, and rubella, varicella) were most commonly reported. Of 350 reports in persons aged ≥19 years, 80% were female, and inactivated influenza vaccines were most frequently reported. Overall, 41% of reports described persons with no history of hypersensitivities (a history of anaphylaxis, respiratory allergies, or allergies to foods, medications, or insect stings). Of 8 reports of anaphylaxis after vaccination where the patient died, 4 were among persons with no history of hypersensitivity, and 5 documented an onset of symptoms within 20 minutes of vaccination.

Su et al.’s data indicate that reports of anaphylaxis after vaccination to VAERS are rare in the United States. Such reports typically describe persons with a history of hypersensitivity, but can describe persons with no history of hypersensitivity. Their data also indicate that most persons recover fully with prompt treatment, but serious complications, including death, can rarely occur. Providers who administer vaccines should be prepared to manage a severe hypersensitivity reaction like anaphylaxis.

The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.