How Common are Anaphylaxis and Allergic Reactions Following Pfizer-BioNTech COVID-19 Vaccination?

BACKGROUND AND PURPOSE:

As of December 23, 2020, over 1.8 million first-doses of Pfizer-BioNTech’s COVID-19 vaccine had been administered in the US
The CDC COVID-19 Response Team (MMWR, 2021) report on cases of allergic reactions, including anaphylaxis, associated with first-dose vaccination

Data sources
- Vaccine Adverse Event Reporting System (VAERS)
Population
- Initial vaccination was suggested for front-line healthcare workers and long-term care facility residents

Initial vaccinations: 1,893,360 first doses
- 0.2% (n=4393) had associated adverse events
Allergic reactions: 175 events
- Anaphylaxis: 21 events
- The overall anaphylaxis rate is 11.1 per million doses administered
17 of these events took place in persons with a documented history of allergic reactions
- 7 of these persons had a history of anaphylaxis
The median interval from vaccine receipt to symptom onset was 13 minutes (range 2 to 150 minutes)
Among the 20 patients with follow-up information available, all recovered
Of the non-anaphylaxis case reports
- 86 were judged to be non-anaphylaxis allergic reactions
- 61 were considered nonallergic adverse events

Anaphylaxis is a rare event after initial vaccination with Pfizer-BioNTech’s COVID-19 vaccine (approximately 11 per million)
Limitations include
- Passive reporting system which could lead to underreporting
- Major media attention which could lead to heightened awareness and lower threshold for early treatment of suspected cases (overreporting)
Currently, the CDC recommends vaccine providers
- Screen for contraindications before administering the vaccine
- Have on hand supplies needed to manage anaphylaxis, should it occur
- Implement post-vaccination observation periods
- Immediately treat persons who exhibit signs of anaphylaxis with intramuscular injection of epinephrine