COVID-19 vaccine side-effects: You get what you expect
New research shows that the side-effects each of us experience after COVID-19 vaccines are linked to our own expectations. If we are expecting side-effects, we are more likely to actually get them. According to the researchers behind the study, especially healthcare professionals should be mindful of this effect.
Do you expect to get a headache, nausea and fever after your COVID-19 vaccination? Then you probably will. The likelihood is certainly more pronounced than if you do not expect these side-effects.
This was shown in a new study just published in the high impact journal Psychotherapy and Psychosomatics.
“Many factors influence which side-effects each individual will get, for instance their age and the type of vaccine. But if we include people’s expectations in this equation, we see a significant change,” says Lene Vase, professor of psychology at Aarhus BSS, Aarhus University, and one of the researchers behind the new study.
The study is the first in the world to uncover this link.
“Naturally, we should inform people about the side-effects, but perhaps we can change the way we give this information.”
Lene Vase, professor of psychology at Aarhus BSS, Aarhus University.
“Based on this knowledge, I would say it is worth considering how to inform people of the vaccines and their side-effects. This is especially true for healthcare professionals, who might have very different ways of presenting people with the possible side-effects. But it also applies to e.g. government authorities and the media,” says Lene Vase.
Placebo’s evil twin
In other areas of healthcare, it is a well-known fact that negative treatment expectations can lead to negative health outcomes. Both mentally and physically.
This effect is called nocebo and can be explained as placebo’s evil twin. Whereas placebo could cause you to experience a positive effect from a calcium tablet because you think it contains effective medicine, nocebo means you experience negative effects from a treatment because you expect negative effects.
“If you expect to have a bad experience, you are more likely to actually have one,” says Lene Vase.
In the new study on COVID-19 vaccines, the researchers asked the participants about their expectations for side-effects prior to vaccination. After vaccination, they asked the participants which symptoms they did in fact experience.
The results show that side-effects such as pain at the injection site, headache, joint pain, fever, nausea and fatigue are particularly influenced by expectations.
Read also: Danskerne fik klar Corona-besked
Probable physical effect
The new study deals solely with the participants’ subjective experiences. For this reason, the researchers cannot say with certainty whether or not negative expectations affected the participants physically. However, Lene Vase strongly suspects this to be the case.
"From general research into nocebo effects, we know that we are dealing with neurobiological effects. For instance, our expectations might trigger the release of neurotransmitters that can increase our experience of pain, which in turn affects our health. I can easily imagine this to be the case for COVID-19 vaccines as well. We will soon learn more about these effects. We are conducting a large Danish study in which we compare people’s experiences with a detailed neurophysiological examination to obtain reliable knowledge about the physical changes,” says Lene Vase.
Read also: Empati kan forebygge COVID-19-spredning
Side-effects impact support for vaccines
According to her, the mere existence of a link between expectations and actual side-effects should give cause for action.
“Naturally, we should inform people about the side-effects, but perhaps we can change the way we give this information. Instead of stating that 5 per cent experience a certain side-effect, we can perhaps mention that 95 per cent do not. We know from other research that it works to address matters in a positive way like this,” says Lene Vase and adds:
“If we are able to reduce the discomfort of being vaccinated – without compromising factual information, of course – this will hold its own reward. And perhaps more people will feel safe having the vaccine.”
Other international studies have shown that people who opt not to have a COVID-19 vaccination are often concerned about the side-effects of the vaccine.
[Translate to English:]
[Translate to English:]
Placebo med omvendt fortegn
Det er kendt fra andre sundhedsområder, at negative forventninger til behandling i sig selv kan give negative resultater. Både psykisk og fysisk.
Effekten kaldes nocebo og kan forklares som placebo med omvendt fortegn. Her er der altså ikke tale om, at man kan få positiv effekt af en kalktablet, fordi man tror, den indeholder effektfuld medicin. Her er der tale om, at man oplever negativ effekt af en behandling, fordi man forventer en negativ effekt.
”Hvis man forventer, at det bliver slemt, er der større sandsynlighed for, at det faktisk bliver slemt,” siger Lene Vase.
I det nye studie om corona-vacciner har forskerne forud for vaccinationen spurgt deltagerne til deres forventninger til bivirkninger. Efter vaccinationen har de så spurgt til, hvilke symptomer deltagerne rent faktisk har oplevet.
Især smerter ved indstiksstedet, hovedpine, smerte i kroppen, feber, kvalme og træthed bliver påvirket af forventningerne, viser tallene.
Læs også: Danskerne fik klar Corona-besked
Formentlig fysisk effekt
Det nye studie handler udelukkende om deltagernes egne subjektive oplevelser, så forskerne kan ikke med sikkerhed sige, at de negative forventninger rent faktisk har påvirket deltagerne fysisk. Lene Vase har dog en kraftig formodning.
”Vi ved fra den generelle forskning i nocebo effekter, at der er tale om neurobiologiske effekter. Forventningerne kan for eksempel føre til frigivelse af neurotransmittere, der kan forstærke smerteoplevelsen, som så igen påvirker vores sundhedstilstand. Jeg kan sagtens forestille mig, at det også gælder med hensyn til corona-vacciner. Det bliver vi snart klogere på. Vi har nemlig en stor dansk undersøgelse på vej, hvor vi sammenholder folks oplevelser med en detaljeret neurofysiologisk undersøgelse for at få sikker viden om de fysiske forandringer,” siger Lene Vase.
Læs også: Empati kan forebygge COVID-19-spredning
Bivirkninger har betydning for vaccinetilslutning
Alene det, at sammenhængen mellem forventninger og faktiske bivirkninger eksisterer, bør give anledning til handling, mener hun.
”Man skal naturligvis informere om bivirkningerne, men måden man gør det på, kan måske ændres. I stedet for at sige, at 5 procent får en bivirkning, kan man måske sige at 95 procent ikke gør. Den form for positiv italesættelse virker, ved vi fra anden forskning,” siger Lene Vase og tilføjer:
”Hvis vi kan reducere generne ved at blive vaccineret – uden at gå på kompromis med faktuel information, naturligvis – er det jo i sig selv en gevinst. Og måske vil flere også være trygge ved at lade sig vaccinere.”
Man ved fra andre internationale undersøgelser, at folk, der fravælger corona-vaccine, ofte er bekymrede for netop bivirkninger ved vaccinen.
[Translate to English:]
[Translate to English:]
Bivirkninger har betydning for vaccinetilslutning
Alene det, at sammenhængen mellem forventninger og faktiske bivirkninger eksisterer, bør give anledning til handling, mener hun.
”Man skal naturligvis informere om bivirkningerne, men måden man gør det på, kan måske ændres. I stedet for at sige, at 5 procent får en bivirkning, kan man måske sige at 95 procent ikke gør. Den form for positiv italesættelse virker, ved vi fra anden forskning,” siger Lene Vase og tilføjer:
”Hvis vi kan reducere generne ved at blive vaccineret – uden at gå på kompromis med faktuel information, naturligvis – er det jo i sig selv en gevinst. Og måske vil flere også være trygge ved at lade sig vaccinere.”
Man ved fra andre internationale undersøgelser, at folk, der fravælger corona-vaccine, ofte er bekymrede for netop bivirkninger ved vaccinen.