Drug Safety and Risk Management Department, Saudi Food and Drug Authority, Saudi Arabia
Background: Anaphylaxis is an immediate type of life-threatening allergic reaction that occurs rarely after vaccination, with time onset within minutes to hours. There is a concern that the polyethylene glycol (PEG), one of the components of the Pfizer-BioNTech COVID-19 vaccine, could trigger this anaphylactic reaction.
Objectives: To assess the potential risk of anaphylaxis reactions reported with the use of the Pfizer-BioNTech coronavirus vaccine.
Methods: This is a descriptive analysis of all anaphylaxis reported cases associated with the use of the Pfizer-BioNTech coronavirus vaccine. On January 31, 2021, we searched in the WHO global individual case safety reports database (VigiBase ), to retrieve reported cases using the terms ‘Comirnaty’ OR ‘COVID-19 mRNA Vaccine BNT162b2’ OR ‘Pfizer BioNTech COVID-19 vaccine’ as drug substance [AND] ‘Anaphylactic reaction’ as reaction-term. In addition, we searched in the local Adverse Drug Reactions database of the National Pharmacovigilance Center in Saudi Arabia. The causality assessment of anaphylaxis reactions was performed using the WHO-Uppsala Monitoring Center causality system.
Results: The search in the WHO database resulted in 446 cases of anaphylaxis with the Pfizer-BioNTech COVID-19 vaccine. In addition, 11 locally reported cases were included in this analysis. No fatal cases were reported from anaphylaxis. For global cases, 140 cases with a completeness score of ≥0.8 were included in the analysis. In all cases, the Pfizer-BioNTech COVID-19 vaccine was reported as an individual suspected drug and 136 patients with anaphylaxis had recovered (97%). The mean age was 46 years (range 19 - 98) and the majority were female (95%). For local cases, anaphylaxis was reported after the first dose except for one case reported after the second dose. The mean age was 53 years (range 34-70) and the majority of cases were female (64%).The most common symptoms reported were shortness of breath (n=11) and vomiting (n=3). All the patients had no history of allergy except one patient had an allergy to tramadol, penicillin, and metoclopramide. The time of onset in all included cases was within one day, which showed a reasonable temporal relationship. The causality assessment showed that all included cases were possibly related.
Conclusions: The results of this analysis show that a reasonable number of patients developed anaphylaxis reactions following the immunization with the vaccine. However, whether the exact source of this reaction is PEG or not is still unknown.