CDC report details allergic reactions after receipt of first dose of Pfizer-BioNTech COVID-19 vaccine

The US Centers for Disease Control and Prevention’s (CDC) latest Morbidity and Mortality Weekly Report details allergic reactions including anaphylaxis after receiving the first dose of Pfizer-BioNTech COVID-19 vaccine in the US.

From December 14 to December 23, 2020, after administration of 1,893,360 first doses of Pfizer-BioNTech COVID-19 vaccine, reports of 4,393 (0.2%) adverse events after receipt of the vaccine had been submitted to the Vaccine Adverse Event Reporting System (VAERS). Among these, 175 case reports were identified for further review as possible cases of severe allergic reaction, including anaphylaxis, based on descriptions of signs and symptoms.

The report noted that 21 of these cases met the Brighton Collaboration case definition criteria for anaphylaxis, corresponding to an initial estimated rate of 11.1 cases per million doses administered. All reports were Brighton levels 1 or 2. The median age of persons with anaphylaxis was 40 years (range = 27–60 years), and 19 (90%) cases occurred in females. Nonetheless, the report highlighted that “whereas a female predominance has been previously observed in a review of immediate hypersensitivity reports to VAERS after influenza A(H1N1) vaccine, the current finding could be impacted by the observation that more women than men had received a first dose of Pfizer-BioNTech COVID-19 vaccine during the analytic period.”

The median interval from vaccine receipt to symptom onset was 13 minutes (range = 2–150 minutes). Most (71.4%) of the patients had onset within 15 minutes, while 14.3% had onset within 15 to 30 minutes, and 14.3% after 30 minutes. 

In 19 of 21 (90%) cases, patients were treated with epinephrine as part of therapy. Meanwhile, 4 (19%) patients were hospitalized (including three in intensive care), and 17 (81%) were treated in an emergency department. At the time of report to VAERS, 20 (95%) patients are known to have been discharged home or had recovered. No deaths from anaphylaxis were reported after receipt of Pfizer-BioNTech COVID-19 vaccine. 

According to the report, 17 (81%) of 21 patients with anaphylaxis had a documented history of allergies or allergic reactions, including to drugs or medical products, foods, and insect stings. Further, 7 (33%) patients had experienced an episode of anaphylaxis in the past, including one after receipt of a rabies vaccine and another after receipt of an influenza A(H1N1) vaccine. 

Additionally, the report noted that no geographic clustering of anaphylaxis cases was observed, and the cases occurred after receipt of doses from multiple vaccine lots. 

Meanwhile, VAERS also identified 83 cases of nonanaphylaxis allergic reaction after Pfizer-BioNTech COVID-19 vaccination with symptom onset within the 0–1-day risk window, 72 (87%) of which were classified as nonserious. Commonly reported symptoms included pruritus, rash, itchy and scratchy sensations in the throat, and mild respiratory symptoms.

“Based on early safety monitoring, anaphylaxis after the Pfizer-BioNTech COVID-19 vaccine appears to be a rare event; however, comparisons of anaphylaxis risk with that associated with non-COVID-19 vaccines are constrained at this time by the limited data available this early in the COVID-19 vaccination program,” the CDC said. “CDC and FDA will continue enhanced monitoring for anaphylaxis among recipients of COVID-19 vaccines.”

source: https://dgalerts.docguide.com/cdc-report-details-allergic-reactions-including-anaphylaxis-after-receipt-first-dose-pfizer-biontech?overlay=2&nl_ref=newsletter&pk_campaign=newsletter&nl_eventid=80854&nl_campaignid=3641&pw_siteID=25&ncov_site=covid-19&MemberID=301406405