Many people who have had the Covid-19 vaccine may experience adverse effects such as fever, pain at the injection site, fatigue and others. But often these effects are only psychological.
A review of 12 articles, including reports of side symptoms that included 45,380 study participants, by researchers at Beth Israel Deaconess Medical Center, Harvard Medical School hospital, indicates that more than half reactions to the coronavirus vaccine are linked. to psychological symptoms.
The study, published in the scientific journal Jama Network Open, showed that about 76% of all common adverse reactions after the first dose and nearly 52% after the second dose are part of what they call the “nocebo effect” — a reverse version. of the placebo effect.
To better understand what the nocebo effect means, Rachel Rieira, a researcher at Sírio-Libanês Ensino e Pesquisa and professor of Evidence-Based Medicine at the Escola Paulista de Medicina de São Paulo (Unifesp), told CNN that it is first necessary to understand what the placebo effect is.
“When a substance is able to mimic, or when a person understands that they are having benefits that they would have as if they were taking a drug, it is called the placebo effect.”
Rieira explains that the nocebo effect is the feeling that the side events that are expected with the active drug are occurring, but when the person receives the placebo.
“The idea of placebo and nocebo are very similar, only we use the term placebo when the person believes they are having the benefits, and nocebo when they think they are having the adverse effects”, he points out.
Alex Lacerda, allergist and immunologist at BP – Beneficência Portuguesa de São Paulo, comments that “our mind is very powerful and cannot be disassociated from our body. It will often manifest symptoms in the body. These effects, both placebo and nocebo, happen mainly out of a belief, by imagining that something is going to happen when you come into contact with the drug.”
Anxiety vs nocebo effect
The feeling of some adverse effect related to the vaccine is often linked to what the person heard or saw somewhere, according to Álvaro Furtado, an infectious disease specialist at the Hospital das Clínicas, Faculty of Medicine, USP (HCFMUSP).
He clarifies that this occurs because the patient is suggested and already knows the adverse events.
“Some effects are more of a psychiatric nature, of an anxiety order, rather than vaccine-related adverse events. Sometimes the stressed, worried person knows some adverse events that a friend told, commented that he had a fever, had pain. So there is an overestimation of something that is small because she knows it or because she has heard about it.”
Lacerda says that people who have anxiety may be more prone to the nocebo effect.
“However, it is important to emphasize that anyone can suffer from this fact and therefore it is necessary to know that they exist, as adverse symptoms are often unrelated to the drug itself.”
This unconscious incorporation of symptoms causes sensations that may be real for the patient, but when the doctor tries to somehow verify, there are no clinical signs, explains Rieira.
“The nocebo effect occurs mainly in adverse events that are not easily measurable by objective tools. Then there are symptoms like a feeling of numbness in the hands, dry mouth, headache. These are signs that the patient refers to, but when they are measured in a subjective way, they are not proven”, he points out.
In the survey, of the 45,380 participants in the studies evaluated, 22,578 were placebo recipients and 22,802 were Covid-19 vaccine recipients. After the first dose, 35.2% of placebo patients experienced headache and fatigue. And 16% reported arm pain or swelling at the injection site.
As expected, the rate of headaches or other systemic symptoms was almost twice as high in the vaccine group (61%) compared to the placebo group (32%).
It’s not just figments of the imagination.
Although more than half of the symptoms are associated with belief or psychological manifestations, the nocebo effect is not a figment of the imagination.
The allergist and immunologist at BP – A Beneficência Portuguesa de São Paulo, says that the nocebo effect can potentiate existing negative symptoms, that is, intensify a pain that was caused by a medication that the patient has already received.
“The most practical example of this is when the person is going to receive benzathine penicillin, popularly known as benzetacil. There is already information that it will hurt and often the person will have more intense pain due to the nocebo effect. In other words, the pain was not the result of imagination, but it was influenced by psychosomatic factors”, explains Lacerta.
Rieira, from Sírio-Libanês, says that this is also common even with people who read the medication package insert.
“We know that there are people who are more suggestible, who cannot read the package insert of a drug because they will feel all the adverse events that could potentially be associated with that drug, even if they do not.”
Despite this, she explains that there are people who really feel it and have manifestations. However, “part of the population, sometimes, from reading, knowing that it can happen, is already suggested.”
How to deal with the nocebo effect
The Beth Israel Deaconess Medical Center researchers responsible for the nocebo effect research wrote that one way to lessen these negative vaccine-related symptoms is by informing the public about the potential for nocebo responses.
This would reduce Covid-19 vaccination concerns, which may lessen vaccination hesitancy.
Lacerda agrees that conveying information correctly can benefit patients.
“A has an excess of negative information that will cause fear and insecurity, which will provide this nocebo effect. In this aspect, it is important for the population to know that there is this event that can often impair the treatment to be performed.”
Rieira, warns that there is no measure to prevent the nocebo effect.
“We don’t even know which patients are subject to this type of effect. So we can’t exactly predict or treat this. We know there are people who are more suggestible — those who have read, listened or are anxious,” she explains.
For the researcher, news about vaccine reactions has two roles: “they are important to know what are the expected vaccine reactions, which happen more frequently because with that the person protects himself more, gets to know his body more and diagnoses , seek medical attention more quickly when they understand that that event may be associated with the vaccine and could be potentially serious.”
In a second moment, Rieira believes that, on the other hand, reading a lot of news about reactions, “most of the time, the effects are mild, it’s not serious, people are suggested to think they are having reactions, but when the doctor goes to measure objectively, the reactions are not proven”, he said.
Furtado, from HCFMUSP, points out that these very exaggerated symptoms of anxiety, in relation to concern about adverse events, can make people stop taking the vaccine.
“So, there are people who really have to follow up with a psychiatrist. Often, people who have anxiety stop taking it. So it is important that the health professional explains, tries to talk to the patient so that he does not stop taking the vaccine.”
Source: CNN Brasil
