It fits the psychosomatic role of “nocebo effects,” the researchers say – when “psychological characteristics including anxiety, depression, and the tendency to amplify benign bodily sensations” cause participants to report more bad effects than others.
In August 2021, researchers in Hamburg, Germany, followed 1,678 adults getting a second shot of Pfizer or Moderna mRNA-based vaccines. Participants reported symptoms in a diary, starting 2 weeks ahead of the vaccinations and going 7 days afterward.
Some participants said they weren’t expecting much benefit. Researchers said these people were more likely to “catastrophize instead of normalize benign bodily sensations.” People who’d had a bad experience with their first shot were more likely to say they felt aches, pains, and other side effects from the second.
The research was published in JAMA Network Open.
“Clinician-patient interactions and public vaccine campaigns may both benefit from these insights by optimizing and contextualizing information provided about COVID-19 vaccines,” the researchers said. “Unfavorable nocebo-related adverse effects could then be prevented, and overall vaccine acceptance could be improved.”
More than half of participants, 52.1%, expected bad effects to happen from the shot. Another 7.6% said they would be hospitalized from those bad effects, and 10.6% said the effects would last in the long term.
The Washington Times reported that “substantial numbers of patients reported adverse effects after vaccination,” but people with positive expectations reported them as minor. “Those who scored higher for anxiety, depression, and other psychosocial factors were more likely to flag these issues as severe.”
A version of this article originally appeared on WebMD.com.