The UK’s Medicines and Healthcare products Regulatory Agency (MHRA) on Wednesday warned that people who have a “significant history” of allergic reactions should not receive Pfizer and BioNTech’s COVID-19 vaccine BNT162b2. The regulator issued the alert because two NHS workers, among the first to be given the mRNA-based vaccine as part of the country’s immunization program, reported anaphylactoid reactions shortly after being dosed.
Last week, the UK government accepted a recommendation from the MHRA to grant temporary authorization of BNT162b2, with the first immunisations of high-risk groups, such as frontline healthcare workers, beginning on December 8. According to the BBC, “several thousand” people were vaccinated in hospital clinics on the first day of the rollout.
NHS medical director Stephen Powis stated that the “precautionary” move was “common with new vaccines.” He noted that the two individuals who experienced the adverse events had “a history of significant allergic reactions,” and that “both are recovering well.”
The MHRA said the vaccine, which is administered in two doses at least 21 days apart, triggered the anaphylactoid reactions in both cases shortly after the recipients got their first dose. The agency reminded healthcare workers that vaccinations should only be carried out in facilities where resuscitation measures are available, and added that it would issue further advice following an investigation.
Reactions not seen in clinical trials
Commenting on the two case reports, MHRA chief executive June Raine said “we know from the very extensive clinical trials that this wasn’t a feature.” Pfizer and BioNTech recently reported fatigue and headache as the only grade 3 adverse events that had a frequency of 2% or more in Phase III testing. Meanwhile, FDA reviewers preparing for an upcoming advisory panel meeting in the US this week, noted that there were cases of lymphadenopathy and Bell’s palsy in some vaccinated study participants, but that most side effects after vaccination, while frequent, were “mostly mild-to-moderate” in nature.
The UK regulator has been criticised by some for allegedly having been too hasty in authorizing the vaccine, with US infectious diseases specialist Anthony Fauci, a member of the White House coronavirus taskforce, calling it a “rushed” decision.
In a statement, Pfizer said that in an ongoing pivotal phase 3 trial, in which over 42,000 participants have received their second dose of the vaccine, BNT162b2 was “generally well tolerated with no serious safety concerns.” Meanwhile, partner BioNTech noted that people with a history of severe allergic reactions to vaccines, medications or any component used in the trial were excluded from the process.
Separately on Wednesday, Health Canada authorized BNT162b2 under an interim order for emergency use of the vaccine to protect people 16 years of age or older against infection with SARS- CoV-2. The European Medicines Agency is also evaluating the vaccine, having started a rolling review in early October.