Is there an allergy risk with the coronavirus vaccine?
The Pfizer/BioNTech shot was the first covid-19 vaccination to be approved for use but two recipients in the UK have reported symptoms of anaphylaxis after taking it.
The UK became the first nation to approve a covid-19 vaccine earlier this month and has already started inoculating the most vulnerable patients and frontline healthcare workers. However despite rigorous testing the Pfizer/BioNTech vaccine has had adverse effects on a small number of allergy sufferers.
Two healthcare workers with a history of significant allergies have reported anaphylaxis after receiving their shots, provoking the British medical regulators to change the guidance around vaccine use. Anaphylaxis is an overreaction of the body’s immune system, often caused by an external stimulus such as an allergy, which can lead to throat swelling and give the patient breathing difficulties. The two cases occurred on the first day of the nationwide roll-out, but were a tiny percentage of the thousands who were treated that day.
How does this change the covid-19 vaccine guidance?
In response to these side effects for certain patients Britain’s medicine regulator, the Medicines and Healthcare Products Regulatory Agency (MHRA), has adjusted its guidance for those with a history of anaphylaxis. Initially, the MHRA advised that anyone who has previously experienced a “significant allergic reaction” should not take the vaccine until more is known about the precise cause.
On Thursday that guidance was updated with a fuller explanation of the risks; a statement from MHRA Chief Executive June Raine said: “Any person with a history of anaphylaxis to a vaccine, medicine or food should not receive the Pfizer BioNTech vaccine.”
However the statement went on to say: “Most people will not get anaphylaxis and the benefits in protecting people against COVID-19 outweigh the risks... You can be completely confident that this vaccine has met the MHRA’s robust standards of safety, quality and effectiveness.”
The proportion of the population who will be affected by this latest guidance (those with a history of serious allergies) is relatively small and health experts have been keen to stress that this has no effect on the majority. Stephen Evans, a professor of pharmacoepidemiology at the London School of Hygiene & Tropical Medicine, clarified: “For the general population, this does not mean that they would need to be anxious about receiving the vaccination.”
Will this new guidance in the UK affect vaccine use in the US?
Canada became the third country to approve a covid-19 vaccine on Wednesday but patients in the US will have to wait for results of the Food and Drug Administration hearing on Thursday. Analysis released by the FDA on Tuesday suggests that the vaccine will be given the emergency use authorisation that it needs for distribution to begin.
The documents did include reference to heightened risk to patients with a history of allergies but found that the increase was relatively small. During the trial of the Pfizer/BioNTech vaccine, patients in the vaccine group experienced adverse allergic reactions at a rate of 0.63%, compared to 0.51% in the placebo group.
Speaking to CNN, vaccine expert Dr Paul Offit said that he believed that the “blanket recommendation” that no one with allergies is given the vaccine was unwise, adding that "the smarter thing to do would be to try and look at these two patients and see what specific component of the vaccine they were allergic to."