Nocebo: Strange effect after vaccination with Covid-19 vaccine

Side effects of drugs can be passed from person to person through the nocebo effect. So if a person who had had a previous vaccination tells you that they are very sore and tired, you are more likely to feel the same pain and fatigue as they did after the injection.

How do you feel after getting the Covid-19 vaccine? For myself, the first injection was an unpleasant experience. For 3 days in a row, I had a fever, muscle aches, especially the arm that received the injection, so swollen that I couldn't hold a towel.

The second injection 2 months later was more comfortable. None of the above side effects repeated for me except for a slight discomfort at the injection site. Most recently, the third injection brought me back to my experiences after the first injection, but all the side effects were mild and didn't last more than 1 day.

Common symptoms after receiving the Covid-19 vaccine.

I used to think that order was obvious, when your body is exposed to a brand new vaccine, your immune system will have to react most strongly. Subsequent boosters will of course be milder, as the body gets used to the presence of Covid-19 antigens.

But after reading a study in the journal JAMA Network Open, it dawned on me that maybe things don't just happen that way. Especially in the first shot, I seem to have gotten caught up in an effect called nocebo, where the overwhelming side effects of the vaccine are just the result of imagination.

I imagined myself getting a fever just to rationalize 2 days off, thinking I was exhausted because a previously vaccinated friend said so. As for the swollen arm, it could have been real - but only a little, not as severe as I described.

All the side effects of the Covid-19 vaccine, for me personally, turned out to be just the nocebo effect.

What is the nocebo effect?

Nocebo in Latin means "I will harm you". The term was first used by Walter Kennedy, an American physician, in 1961 to refer to a person's negative expectations for a medical therapy leading to its negative side effects.

Nocebo therefore derives from the patient's own imagination and not from the actual medicinal properties of the drug or therapy. For example, when you read the instructions for a medication and pay too much attention to or worry about its side effects, you are more likely to experience those side effects in real life.

Hundreds of studies and randomized controlled trials conducted over the past half century have shown that: When doctors carefully explain the side effects of a drug to two groups of patients, then another took the real drug and one group took a placebo (which are capsules containing only an inert substance like starch), both groups experienced side effects explained by their doctor.

In the group that received the actual drug, those side effects could be explained by the drug's pharmacokinetics. But in the placebo group, it was certainly just the nocebo.

And even if the drug side effects were real, being affected by nocebo would cause patients in the real pill group to experience more severe side effects. This also counts as a form of nocebo.

Nocebo therefore comes from the patient's own imagination, not from the medicinal properties of the drug.

Returning to the new study in the journal JAMA Network Open, the authors from Harvard Medical School analyzed a total of 12 clinical trials involving 45,380 people. Among them, 22,802 people received the real Covid-19 vaccine and the remaining 22,578 patients received a placebo (saline injection). None of the participants knew if they had received the real vaccine or a placebo.

After the first injection, 46.3% of people who received the actual vaccine reported systemic side effects, the most common being headache and fatigue. A higher rate, 66.7% reported local side effects, such as soreness or swelling at the injection site.

But patients taking placebo also experienced those side effects, with 35.2% reporting systemic effects and 16.2% reporting local side effects.

Based on ratio comparisons between the two groups, the Harvard researchers' analysis concluded: The nocebo effect caused a total of 76% of systemic adverse events and 24% of local effects after the first dose of vaccine. The number for the second injection was slightly lower, but still at 52%.

That means many of us feel pain at the injection site, fatigue or even fever after getting the Covid-19 vaccine, it's more than likely just a nocebo effect and I would count myself in the group of those. who have experienced it.

Why when we imagine, nocebo come true?

The origin of each specific nocebo effect remains largely a mystery to scientists. But one thing is for sure, they know the nocebo is a product of the brain itself. Because a placebo is completely chemically inert, it cannot trigger any chemical reactions in your body.

But the human mind, on the contrary, is something very powerful. Not only is the mind capable of convincing us to believe something, but it also causes the body to produce false symptoms based on some mysterious biochemical and neurological pathways.

An example of the nocebo effect of aggravating pain.

"It's the power of imagination," said Dr. John Kelley, associate director of the placebo-research program at Harvard Medical School. you can see on their MRI scans that their occipital lobes - the part of the brain involved with vision - are activated.

If you tell people to imagine doing some physical activity, you'll see their motor cortex activate. Just imagining something happening is enough to activate areas of the brain associated with that thought, including anxiety or pain."

In case you think you'll have a fever, fatigue, or arm pain after the Covid-19 vaccine, it's possible that the very parts of your brain involved in the fever, fatigue and pain response will be activated. And the brain begins to convince you to believe it, with a series of biochemical reactions.

Scientists have found in placebo-controlled studies that the nocebo effect can trigger more severe pain by inhibiting the area of ​​the brain that releases dopamine, a nerve agent that relieves pain, and increases the release of chlorecystokinin, a chemical that promotes pain in the body, making you more sensitive to them.

That's why I think my pain after the Covid-19 vaccine is just imaginary. And it's also triggered by a number of other, more psychological factors.

The nocebo scientists say this effect may be further triggered by the way doctors and nurses talk about the drug's side effects. A 2016 study in the journal Pharmacology, Research & Perspectives found that the more a doctor talked about a therapy's negative effect, the stronger it triggered the nocebo effect.

This is exactly what I experienced with the first Covid-19 vaccine. The doctors gave me a follow-up leaflet that listed all the side effects of the vaccine and explained them very carefully.

But by the second and third injections, the injection unit no longer gave me those follow-up instructions and strangely, the side effects of the vaccine also lessened or even disappeared.

"Many fact sheets list non-specific side effects," said Ted J. Kaptchuk, one of the new study authors at Harvard Medical School and a world-leading researcher in the field of placebo. Covid-19 vaccine such as headache and fatigue, which are also symptoms that have been shown to be particularly susceptible to nocebo.

Evidence suggests that this kind of information can lead people to misallocate basic feelings they encounter on a daily basis and attribute it to vaccines, or make them anxious and overly attentive to how their bodies are feeling. and adverse events".

The second psychological factor that triggers the nocebo effect is past treatment experience. If you ask about side effects experienced by someone who had previously received the Covid-19 vaccine and they elaborately or amplify them to you, you are more likely to experience the same side effects because you I planted an expectation in my head.

Likewise, studies show that media coverage, google searches, and social media discussions can also influence the nocebo effect.

Previous research has shown that as more and more people talk about statin-induced myalgia on the internet, more and more patients experience pain and quit the treatment, despite objective clinical trials. showed that statins did not cause muscle pain. As a result, as more people quit statins, the percentage of patients experiencing heart attacks and strokes also increases.

The same may be true of Covid-19, the researchers say, when more people are worried about vaccine side effects that they won't get vaccinated and put themselves at risk of contracting the disease.

The trigger for the nocebo effect is past treatment experience.

Factors that trigger the nocebo effect: Self-imagining, from medication instructions or given by a doctor, and seeing from other people's experiences.

Drug cost also has an effect on the nocebo effect. In a 2017 experiment published in the journal Science, scientists gave a group of volunteers the choice of using an expensive or inexpensive skin cream and said they could treat itching but had side effects of: cause skin irritation.

The results showed that people who chose the expensive drug said they felt less itching but also had more skin irritation than the group who chose the cheaper drug. However, the first surprise was that the cream contained in both expensive and cheap medicine boxes was the same. The second surprise was that they were all placebos, and didn't work for the itch and didn't sting someone's skin.

In the case of Covid-19, the price or type of vaccine can also affect the nocebo effect you experience. For example, many people believe that the side effects of one vaccine are more severe than another, the nocebo effect they get after receiving the vaccine will also correspond to their beliefs.

Finally, the Covid-19 pandemic itself and vaccine anxiety are also counted as an aggravating factor for the nocebo effect. A 2020 study in the journal Frontiers in Psychology says Covid-19 is "a perfect storm in which nocebo effects can blossom".

When we are pushed into an uncertain situation, exposed to a lot of negative information about pandemics and vaccines, and conversely lack of positive references, the nocebo is also more likely to appear.

How to limit the nocebo effect?

Clearly, the nocebo is putting doctors in a difficult position. If they inform patients about the potential risks and negative side effects of a treatment, patients may believe they will experience those harmful outcomes - and nocebo can turn that belief It became a self-fulfilling prophecy.

But if doctors don't tell patients about the risks in advance, they can be sued because medical law and ethics require doctors not to overlook any side effects of therapy before getting their consent. the patient's voluntary consent.

So what's the solution? Kaptchuk says informing patients about the effects of nocebo can help reduce the number of adverse reactions. "Medicine is based on trust," he said.

"Our findings suggest that informing the public about the possibility of them encountering nocebo may help reduce anxiety about Covid-19 vaccination, which may reduce vaccination procrastination. ".

Our psyche can be easily deceived, but we can also reassure it ourselves.

In addition, physicians may use side effect reporting strategies such as placing it next to a drug's positive effect to highlight the drug's effectiveness against the side effect.

They can also explain that listing vaccine side effects or side effects in medication instructions is a must, not everyone experiences that side effect.

So, instead of saying, "You may have aches, fever or fatigue after getting the vaccine," doctors might opt ​​for a different message: "Many people don't see any side effects after getting the vaccine, only a smaller fraction felt achy, feverish, or mildly fatigued."

Instead of saying the vaccine could put you at risk for anaphylaxis, your doctor should emphasize that it is a very rare side effect. If possible, they should give a number such as 1 in 2 million people who get vaccinated in that situation.

For individuals alone, being aware that you may fall into the nocebo effect after vaccination can also help you beat it. Our psyche can be easily deceived, but we can also reassure it ourselves.