On Wednesday, the United Kingdom began rolling out the Pfizer BioNTech COVID-19 vaccine. According to the head of Britain’s medicine regulator, two individuals had allergic reactions shortly after receiving it. Both have since recovered.
The two people are National Health Service (NHS) employees with histories of allergic reactions, and they carry epinephrine auto-injectors (EpiPens). Reactions to vaccines, including to the annual flu vaccine, are uncommon, but they do occur.
According to Prof. Peter Openshaw, an expert in immunology at Imperial College London, “The fact that we know so soon about these two allergic reactions and that the regulator has acted on this to issue precautionary advice shows that this monitoring system is working well.”
In a statement, Pfizer write: “As a precautionary measure, the [Medicines and Healthcare products Regulatory Agency (MHRA)] has issued temporary guidance to the NHS while it conducts an investigation in order to fully understand each case and its causes. Pfizer and BioNTech are supporting the MHRA in the investigation.”
They continue: “In the pivotal phase 3 clinical trial, this vaccine was generally well-tolerated, with no serious safety concerns reported by the independent data monitoring committee. The trial has enrolled over 44,000 participants to date, over 42,000 of whom have received a second vaccination.”
Prof. Saad Shakir, director of the Drug Safety Research Unit, in the U.K., observes: “The summary of product characteristics [SmPC] for the Pfizer vaccine includes a statement saying that this vaccine should not be given to people with hypersensitivity to active substances. A list of active substances was included in the SmPC, but this was not specific.”
He concludes: “It seems that the advice now has been upgraded so that people should not be vaccinated with this vaccine if they have a history of allergic reactions severe enough to require them to use an EpiPen […] when they get a severe allergic reaction. This is the correct risk minimization action.”