Registry data reveal symptoms, outcomes of anaphylaxis from COVID-19 vaccination

PHOENIX — Anaphylaxis accounted for 15% of the adverse reports from clinicians after mRNA vaccinations for COVID-19, according to a late-breaking abstract at the American Academy of Allergy, Asthma & Immunology Annual Meeting.

Anaphylaxis appeared more common following vaccination with Pfizer-BioNTech and among white women. Although most of these patients received emergency treatment, few required hospitalization and none were treated in the ICU, results showed.

Evidence-based information about side effects can combat vaccine hesitancy in the wake of hypersensitivity reactions reported after COVID-19 vaccinations became available, the researchers said in the study, noting the CDC reports that approximately five people per 1 million vaccinated against COVID-19 have experienced anaphylaxis.

The researchers abstracted anaphylaxis events reported to the Massachusetts General Hospital (MGH) and Harvard Medical School COVID-19 Vaccine Allergy Case Registry between Feb. 13, 2021, and Oct. 22, 2021.

The allergist-led, U.S.-based registry collects and shares reports of reactions following COVID-19 vaccination including rashes, swelling and anaphylaxis. Reactions may be reported by patients or by health care providers. Health professionals typically complete the individual case forms used in reporting in 10 to 20 minutes.

Data points include health professional information, patient demographics, vaccine site and dose, reaction characteristics, treatment, medication and exposure history, post-reaction allergist consultation, vaccine allergy skin testing, prior personal COVID-19 history, and prior food or drug allergies including anaphylaxis.

“The allergist community at MGH identified a need to characterize hypersensitivity reactions because, in the beginning, these data weren’t available,” Jordon Jaggers, MD, resident physician in internal medicine at MGH, told Healio.

“This registry was created and is ongoing, and now we are actively analyzing the data in efforts to be transparent about allergic side effects and as a method to assuage vaccine hesitancies,” she continued.

To date, the registry collected 2,186 cases reported by patients and 481 reported by health care providers.

This analysis included 455 unique patients from 44 U.S. states, including 68 patients (mean age, 42 years; standard deviation, 18; 88% female; 82% white) who experienced potentially anaphylactic reactions after COVID-19 vaccination.

Doses included the Pfizer-BioNTech (71%), Moderna (25%) and Johnson & Johnson/Janssen (1%) vaccines, with 3% unknown. Fifty-five (81%) of these reactions occurred after the initial dose.

Medical histories among the patients included atopic disease (56%), asthma (41%), prior anaphylaxis (41%), allergic rhinitis (32%) and chronic urticaria (7%). Previous reactions were triggered by medication (18%), food (16%), venom (6%) and idiopathic causes (3%).

Also, 60% experienced symptoms 15 minutes after vaccination, and 81% experienced them within 30 minutes. Anaphylactic reactions to the vaccines involved the respiratory tract (68%), skin/mucosa (63%), cardiovascular system (28%) and gastrointestinal system (7%).

Respiratory symptoms included shortness of breath (41%), sensation of throat closure (34%), wheezing (13%), dry cough (12%) and upper airway swelling (10%). No patients experienced low oxygen saturation.

Dermatologic symptoms included swollen lips, tongue or uvula (24%); other swelling or angioedema (28%); generalized urticaria (24%); itching (19%) and other unspecified rash (12%).

Common cardiovascular symptoms included high heart rate (18%) and high blood pressure (10%), whereas few patients experienced chest tightness, low blood pressure or syncope. None of the patients experienced bradycardia or other arrhythmia.

Gastrointestinal symptoms, which were infrequent, primarily included nausea and abdominal pain.

Additionally, 62% of these reactions required treatment in the ED, but only 4% required hospitalization, whereas 11% were treated at home. The remainder were treated at urgent cares, retail pharmacies and vaccine or allergy clinics. Treatments included H1-blockers (76%), oral steroids (22%), IV steroids (29%), and intramuscular epinephrine (38%) or epinephrine drip (3%), with 12% requiring no treatment.

“Most reassuring is that very few patients required hospitalization,” Jaggers said. “No one was treated in the intensive care unit, and no deaths were reported.”

According to the researchers, 56 of these patients followed up with an allergist evaluation, and 88% of them were diagnosed with confirmed or possible anaphylaxis. The remaining seven (12%) were found to be inconsistent with anaphylaxis, with five of these reports attributed to patient anxiety.

The researchers then noted the key role that allergists can play in distinguishing between suspected and true anaphylaxis, and they said that they plan on continuing their work as well.

“We plan to send follow-up surveys to patients and healthcare professionals to see whether they went on to tolerate their second or booster doses of the vaccine and collect additional information,” Jaggers said.

The registry is still open to both clinicians and patients, and data can be entered online.