What UK's Allergic Reaction Cases Mean For Pfizer COVID-19 Vaccine

Britain's medicine regulator said anyone with a history of anaphylaxis or significant allergies to a medicine or food should not get the Pfizer-BioNTech COVID-19 vaccine, giving fuller guidance on an earlier allergy warning about the shot. This after three people reported adverse reactions on the first day of its rollout in the UK.

NHS

Starting with the elderly and frontline workers, Britain began mass vaccinating its population on Tuesday, part of a global drive that poses one of the biggest logistical challenges in peacetime history.

Here are some questions and answers about the cases and what they might mean.

What has happened exactly?

The Medicines and Healthcare Products Regulatory Agency (MHRA) said there had been two reports of anaphylaxis and one report of a possible allergic reaction since rollout began.

Anaphylaxis can cause throat swelling, breathing trouble and difficulty swallowing, according to the American Academy of Allergy, Asthma & Immunology. The condition is an overreaction of the body's immune system, which the National Health Service describes as severe and sometimes life-threatening.

Even in the US, four volunteers who were administered the vaccine in the trial stage developed Bell's palsy. According to US Food and Drug Administration (FDA) regulators. Bell's palsy is a form of temporary facial paralysis.

AP

The person suffering from Bell¡¯s palsy develops temporary weakness or paralysis of the facial muscles. The paralysis usually occur when a nerve that controls the muscles becomes inflamed, swollen or compressed.

AP

Who shouldn't get the vaccine as per UK regulators?

Further, MHRA Chief Executive June Raine said in a statement, "Any person with a history of anaphylaxis to a vaccine, medicine or food should not receive the Pfizer BioNTech vaccine."

"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 fuller guidance, clarifying that the main risk was from anaphylaxis specifically, was issued after consulting experts on allergies. The MHRA had initially advised anyone with a history of a "significant allergic reaction" not to take the shot.

Reuters

How does this affect propects for US authorisation?

US regulators are expected to consider emergency authorization of the Pfizer vaccine soon after a Thursday meeting of advisers.

Moncef Slaoui, who is spearheading the US government's vaccine development efforts, said on Wednesday he expected the British allergic reactions would be considered in the US authorization process and that people with known severe allergic reactions probably should not take the vaccine until more was understood.

The US FDA regulators, however, noted that it was still unclear how Bell's palsy was caused in these volunteers due to Pfizer vaccine. The US regulators stressed that doctors should closely monitor the side effect of the vaccine and continue to watch on how many people it strikes.

Reuters

What do doctors say?

Stephen Evans, professor of pharmacoepidemiology at the London School of Hygiene & Tropical Medicine, told the UK's Science Media Centre that the increase was only "small" but said there was "a lot of uncertainty around that estimate."

He said that "some people won't know if they have hypersensitivity to some constituents of the vaccine."

He backed the MHRA advice for people who carry an EpiPen to delay having a vaccination until the reason for the allergic reaction has been clarified. But he said the news did not mean the general public should be anxious.

Prof Peter Openshaw, an expert in immunology at Imperial College London, said: "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."

Vaccine expert Dr. Paul Offit told CNN that allergic reactions to vaccines were not uncommon: "Certainly, vaccines can cause severe allergic reactions. In the United States, roughly one of every 1.4 million doses of vaccines is complicated by a severe allergic reaction."

He said that rather than a "blanket recommendation" for people with allergies, "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."

Last week, Britain's MHRA became the first in the world to approve the vaccine, developed by Germany's BioNTech and Pfizer, while the US FDA and European Medicines Agency (EMA) continue to assess the data.