Anaphylaxis Rates Dropped During COVID-19 Pandemic

Jordan Trevisonno, MDCM

New data presented at the American Academy of Allergy, Asthma & Immunology Annual Meeting (AAAAI) 2022 annual meeting shows anaphylaxis rates actually decreased in emergency department (ED) visits during the initial part of the COVID-19 pandemic in comparison to rates in the years prior to the pandemic.

A team, led by Jordan Trevisonno, McMaster University, assessed emergency department cases of suspected anaphylaxis at a hospital affiliated with McMaster University in Hamilton, Ontario and analyzed the impact COVID-19 had on presentations to the emergency department.

In the study, the investigators used data from the Cross-Canada Anaphylaxis Registry (C-CARE), a national study assessing the causes and management of anaphylaxis.

They also collected demographic, clinical presentation, and management data.

Anaphylaxis Presentations

The team identified cases of suspected anaphylaxis from St Joseph’s Healthcare Hamilton’s Emergency Department using criteria from the National Institute of Allergy and Infectious Diseases/Food Allergy and Anaphylaxis Network (NIAID/FAAN).

There were 994 total encounters for allergic reactions between January 2018 and July 2020, 19.5% (n = 194) of which met the criteria for anaphylaxis.

There were 175 cases over 773 data (0.226 cases per day) of anaphylaxis prior to the COVID-19 restrictions, compared to 19 cases over 132 days (0.144 cases per day) between March and July 2020.

Revising Cases

There were also several cases found that originally were deemed to be anaphylaxis, but later were identified as not being anaphylaxis.

Only 54.2% (n = 149) of the 275 cases initially labelled anaphylaxis met the criteria. Some of the common alternative diagnoses included forms of urticaria (21.4%; n = 27), angioedema (20.5%; n = 26), and oral allergy syndrome (12.6%; n = 16).

“There was a decrease in ED presentation for anaphylaxis during COVID-19 pandemic restrictions,” the authors wrote. “With the low threshold for treating anaphylaxis upon ED presentation, alternative diagnoses included forms of urticaria or angioedema with oral mucocutaneous involvement.”

Anaphylaxis and Vaccinations

Last year, an investigation into allergic reactions from the Pfizer-BioNTech (BNT162b2) COVID-19 vaccine suggested that most patients with allergic diseases could be safely immunized by using an algorithm that incorporated a referral center, a risk assessment questionnaire, and a setting for immunization under medical supervision of highly allergic patients.

In the clinical trials of the BNT162b2 COVID-19 vaccine, participants with a history of allergic reaction to any component of the vaccine or any other vaccine were excluded.

Though rare, allergic reactions to the BNT162b2 were recorded, with the anaphylaxis rate reported to be 4.7 cases per 1 million doses.

To combat uncertainty, the Centers for Disease Control and Prevention (CDC) published safety recommendations of the vaccines for patients with allergic reactions.

Anaphylaxis was documented in 3 (0.7%) patients, who were treated with adrenaline, antihistamines, and an inhaled bronchodilator.

Nonallergic adverse events occurred in 10 (2.3%) patients, but most vaccinated highly allergic individuals did not develop any immediate adverse events.

The study, “Impact of COVID-19 Restrictions on Anaphylaxis Presentations to the Emergency Department,” was published online in the Journal of Allergy and Clinical Immunology.