What you didn't know about volunteering for the Pfizer vaccine 3:54
(CNN Spanish) -
Allergic reactions to a vaccine are not common.
According to the Centers for Disease Control and Prevention (CDC, for its acronym in English), anaphylactic reactions occur 1.3 times per million vaccines administered.
But, two cases of severe allergic reactions in the UK after receiving the Pfizer vaccine have the world wondering: why did we not learn of these reactions during clinical studies?
In this episode, Dr. Elmer Huerta explains why some people have vaccine allergies and what could have caused the allergic reaction in the two Britons.
Patients are recovering well after the reaction.
You can listen to this episode on Apple Podcasts, Spotify, or your favorite podcast platform, or read the transcript below.
Hello, I am Dr. Elmer Huerta and this is your daily dose of information about the new coronavirus, information that we hope will be useful to take care of your health and that of your family.
The Pfizer vaccine: the allergic reaction of two patients
The news came from the UK, the first country to launch a national Covid-19 vaccination program using Pfizer's vaccine.
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According to what was revealed, two health workers who received the vaccine presented anaphylactoid reactions, for which they had to be treated urgently.
As a consequence, British health authorities warned that people with a history of severe allergic reactions to medicines and foods should not receive the Pfizer vaccine.
They also warned that the vaccine should only be administered in health centers that have the ability to resuscitate patients.
Today we will see what an anaphylactic and anaphylactoid type allergic reaction is;
Why is it that this type of reaction is only known with the use of the Pfizer vaccine, and, above all, what news we should be attentive to during the next few days to know if people who suffer from any type of allergy should use that vaccine or not.
Allergic reaction to a vaccine
First of all, we must know that allergies are not a sign of weakness of the defense system, and that because a very common belief is that allergies would mean that the immune system of the sufferer "is weak" and that it needs to be "Strengthened."
It is a great mistake, and the thing is the other way around.
Allergies indicate that the defense system is really strong and intact and that it is acting with greater intensity than normal.
Allergies occur when a person's immune system reacts with extreme intensity to a foreign substance in the body.
That substance, called an allergen, can include:
Pollen from plants,
The proteins found in the saliva of dogs and cats and found in the hair of these animals,
The dust of the feathers and body of cockroaches,
Some types of food, medicines, vaccines
And many other substances
In an allergic reaction, the allergen triggers a very strong immune system response, causing large, plump blood
cells
(
mast cells
), full of chemicals, including histamine,
they burst and release these substances into the blood.
Symptoms of an allergic reaction
That histamine, and other related chemicals, are the cause of allergy symptoms, which can be as simple as a few bumps on the skin, to more intense they include:
Weakness,
Fatigue,
Feeling of fever
Crying eyes,
Nasal catarrh
Itchy eyes, nose and throat
Or even more severe, with asthma attacks
The most serious allergic reactions are called anaphylactic reactions and present with severe hives on the skin, swelling of the eyelids, lips, and larynx, which can cause suffocation in the affected person.
So-
called
anaphylactic
shock
is the most serious allergic reaction and can lead to death.
For their part, anaphylactoid reactions - which were those presented by the British volunteers who received the Pfizer vaccine - have almost the same symptoms as anaphylactic reactions, but due to their mechanism of action, they are less severe.
While it is true that mild allergic reactions to vaccines are not uncommon, severe allergic reactions, that is, anaphylactic reactions are happily very rare.
Allergic reactions to vaccines are rare
A study by the Centers for Disease Control and Prevention, published in the Journal of Allergy and Clinical Immunology in February 2018, estimates that anaphylactic reactions occur 1.3 times per million vaccines administered.
The causes of allergies can be due to the main component of the vaccine (called antigen) or to the chemical compounds that are used to stabilize or enhance the action of the vaccine or to some substances used in its development, such as chicken eggs.
In this regard, one of the most common causes of allergy to vaccines - especially against the flu - occurs in people who are allergic to egg whites.
This is because the manufacture of some vaccines, such as influenza, rabies and yellow fever, is done in chicken embryos in eggs.
Allergies related to egg white can also occur in vaccines grown in chicken embryo cells, such as the triple vaccine or against measles, mumps and rubella.
What Causes the Allergic Reaction in the Pfizer Vaccine?
In the case of the Pfizer vaccine, it is unknown which element may have caused the allergic reaction in the two British vaccinates.
It is possible that it is the messenger RNA, some stabilizer or preservative, and even the layer of nano particles of fat that cover the mRNA molecule, which is the vaccine itself.
In this regard, it is important to say that both people had what is called a severe history of allergy to multiple foods and medications.
It was so so that both people carried adrenaline injections in their wallets, just in case they had severe allergic reactions at some point of the day.
In practical terms, it is important to know that anyone with a history of severe food or drug allergies should speak with their doctor first before getting the Pfizer vaccine.
On the other hand, it is also important to know that in the phase 1, 2 and 3 studies, which included more than 40,000 people, these allergic reactions were not observed.
This could be explained because due to the need to have very well controlled studies with homogeneous volunteers, people with a history of allergies were not included in the study.
As with the approval of new drugs, many side effects are only just beginning to be discovered when the product becomes widely used in the community.
We are confident that, in the coming weeks and months, some other side effects will begin to be detected and documented in all the vaccines that have been developed against covid-19.
Do you have questions about the coronavirus?
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You can find me at @DrHuerta.
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Thanks for your attention.
If you have any questions you can send them to Dr. Elmer Huerta via Twitter. You can also head over to CNNE.com/coronaviruspodcast for all episodes of our “Coronavirus: Reality vs. Reality” podcast. fiction".
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