Medical Expert Endorsement Fails to Reduce Vaccine Hesitancy in U.K. Residents, Journal of Trial & Error, 2023.

ABSTRACT
In this report we outline the null findings of a pre-registered experiment on vaccine hesitancy in the United
Kingdom. The experiment targeted vaccine misconceptions common among participants by presenting a
correction to such claims endorsed by a group of medical experts. The experiment had the aim to increase
vaccination intention and actual uptake during the 2021 COVID-19 vaccination campaign. Our results revealed
that, contrary to a similar study conducted with Italian residents, our intervention was unsuccessful in changing
participants’ attitudes and behaviour towards COVID-19 vaccines. The report concludes with a discussion of
the potential reasons for these null findings.

Keywords: expert endorsement, vaccine hesitancy, nudging, debunking, COVID-19

Take Home Message
An intervention based on medical expert endorsement may not have been
successful in improving vaccination intention and actual uptake during the 2021
COVID-19 immunisation campaign in the United Kingdom. The message campaign that was specifically built
on experts’ advice did not change participants’ views or behaviour concerning COVID-19 vaccinations. Further
research is needed to determine why a similar intervention succeeded in an Italian sample but not among
respondents in the United Kingdom.