London (CNN) – People with a ‘significant history of allergic reactions’ should not receive the Pfizer / BioNTech coronavirus vaccine, UK health authorities said on Wednesday, after two health workers experienced symptoms after receiving an injection. the previous day.
The cautionary advice came after these two people “responded adversely” after their vaccinations on the first day of the mass launch of the vaccination in the UK, England’s National Health Service said on Wednesday.
The two staff members, who were carrying an adrenaline auto-injector and had a history of allergic reactions, developed symptoms of an anaphylactoid reaction after receiving the vaccine on Tuesday. Thousands in total were vaccinated in the UK on Tuesday, NHS England told CNN on Wednesday.
«As is common with new vaccines, the MHRA [Agencia Reguladora de Medicamentos y Productos Sanitarios] has cautioned against vaccinating people with a significant history of allergic reactions, after two people with a history of significant allergic reactions responded adversely yesterday, ”Stephen Powis, National Medical Director for NHS England, said in a release. “They are both recovering well.”
The MHRA issued new advice for healthcare professionals stating that anyone with a significant allergic reaction to a vaccine, drug or food, such as a previous history of anaphylactoid reaction, or those who have been recommended to carry an adrenaline autoinjector , should not receive the Pfizer / BioNtech vaccine.
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The council also states that the vaccines “should only be given in facilities where resuscitation measures are available.”
What is an anaphylactoid reaction and how is it different from anaphylaxis?
According to the Library of Medicine of the US National Institutes of Health. anaphylaxis “is a fatal or life-threatening acute hypersensitivity reaction.” Airway obstruction, skin reactions and other cardiovascular symptoms “including hypotension and gastrointestinal symptoms” may occur. The reaction may begin minutes after exposure to the antigen or “a late phase reaction may occur hours after the initial reaction.”
The Library explains that the reaction can be generated by either “IgE-mediated” (immunoglobulin E) factors or not. If the reaction belongs to the first group it can be called anaphylaxis, but if it is not mediated by IgE, it is called an anaphylactoid reaction.
Pfizer / BioNTech vaccine allergic reaction investigated
“We are thoroughly investigating the two reports as a matter of priority,” said an MHRA spokesman.
“Once all the information has been reviewed, we will communicate the updated advice,” added the spokesperson.
Anyone with a history of a significant allergic reaction due to receiving the Pfizer / BioNTech vaccine was advised to speak with the healthcare professional administering the vaccine.
Pfizer said in a statement that the UK regulator had informed it of “two reports of yellow cards that may be associated with an allergic reaction” due to the administration of the vaccine.
“As a precautionary measure, the MHRA has issued temporary guidance to the NHS while conducting an investigation to fully understand each case and its causes. Pfizer and BioNTech are supporting MHRA in the investigation, ”the statement said.
‘In the pivotal phase 3 clinical trial, this vaccine was generally well tolerated and the independent Data Monitoring Committee reported no serious safety concerns. The trial has enrolled more than 44,000 participants to date, more than 42,000 of whom have received a second vaccine.
Documents released Tuesday by the U.S. Food and Drug Administration (FDA) said data from the Pfizer / BioNTech trial indicated there were potentially slightly more adverse responses believed to be allergic reactions among the group of the vaccine compared to the placebo group, by 0.63% compared to 0.51%.
The Pfizer trial protocol shows that people with a history of severe allergic reactions (eg, anaphylaxis) “to any component of the study intervention” could not participate.
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Stephen Evans, professor of pharmacoepidemiology at the London School of Hygiene and Tropical Medicine, told the UK Science Media Center that the increase was only “small” but said there was “a lot of uncertainty around that estimate.”
He said that “some people will not know if they have hypersensitivity to some components of the vaccine.”
He supported the MHRA’s advice for people carrying an EpiPen to delay vaccination until the reason for the allergic reaction is clarified. But he said the news didn’t mean the general public should be anxious.
Peter Openshaw, professor of experimental medicine at Imperial College London, said: ‘As with all foods and medicines, there is a very small chance of an allergic reaction to any vaccine.
“The fact that we know about these two allergic reactions so early and that the regulator has acted on them to issue precautionary advice shows that this monitoring system is working well.”
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