Negative Expectations of COVID Shots May Amplify Side Effects

Jay Croft

March 31, 2023

People who had low hopes from a COVID-19 vaccine reported more negative side effects from the shots in a study released this week.

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 two weeks ahead of the vaccinations and going seven days after it.

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."


JAMA Network Open: "Expectations and Prior Experiences Associated With Adverse Effects of COVID-19 Vaccination"

The Washington Times: "Study finds negative attitudes amplify vaccine side effects"


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