Prevalence of Allergic Reactions After Pfizer-BioNTech COVID-19 Vaccination Among Adults With High Allergy Risk

Question  Can patients at high risk for anaphylactic reactions receive the Pfizer-BioNTech (BNT162b2) COVID-19 vaccine?

Findings  In this cohort study of 8102 individuals with an allergy history, an algorithm was used to define 429 (5%) as “highly allergic”; this group was referred to receive immunization under medical supervision. A total of 98% of the highly allergic individuals had no allergic reaction, 6 (1%) had mild allergic responses, and 3 (0.7%) had anaphylactic reactions.

Meaning  This study’s findings suggest that a simple algorithm enables immunization of most patients with a history of allergy, while only patients defined as highly allergic should receive vaccination under medical supervision.

Importance  Allergic reactions among some individuals who received the Pfizer-BioNTech (BNT162b2) COVID-19 vaccine discourage patients with allergic conditions from receiving this vaccine and physicians from recommending the vaccine.

Objective  To describe the assessment and immunization of highly allergic individuals with the BNT162b2 vaccine.

Design, Setting, and Participants  In a prospective cohort study from December 27, 2020, to February 22, 2021, 8102 patients with allergies who applied to the COVID 19 vaccine referral center at the Sheba Medical Center underwent risk assessment using an algorithm that included a detailed questionnaire. High-risk patients (n = 429) were considered “highly allergic” and were immunized under medical supervision.

Exposures  Pfizer-BioNTech (BNT162b2) COVID-19 vaccine.

Main Outcomes and Measures  Allergic and anaphylactic reactions after the first and second doses of BNT162b2 vaccine among highly allergic patients.

Results  Of the 429 individuals who applied to the COVID-19 referral center and were defined as highly allergic, 304 (70.9%) were women and the mean (SD) age was 52 (16) years. This highly allergic group was referred to receive immunization under medical supervision. After the first dose of the BNT162b2 vaccine, 420 patients (97.9%) had no immediate allergic event, 6 (1.4%) developed minor allergic responses, and 3 (0.7%) had anaphylactic reactions. During the study period, 218 highly allergic patients (50.8%) received the second BNT162b2 vaccine dose, of which 214 (98.2%) had no allergic reactions and 4 patients (1.8%) had minor allergic reactions. Other immediate and late reactions were comparable with those seen in the general population, except for delayed itch and skin eruption, which were more common among allergic patients.

Conclusions and Relevance  The rate of allergic reactions to BNT162b2 vaccine, is higher among patients with allergies, particularly among a subgroup with a history of high-risk allergies. This study suggests that most patients with a history of allergic diseases and, particularly, highly allergic patients can be safely immunized by using an algorithm that can be implemented in different medical facilities and includes a referral center, a risk assessment questionnaire, and a setting for immunization under medical supervision of highly allergic patients. Further studies are required to define more specific risk factors for allergic reactions to the BNT162b2 vaccine.