Efficacy Information Influences Intention to take COVID-19 Vaccine

Colin J Davis, Matt Golding, Ryan McKay

Research output: Contribution to journalArticle (Academic Journal)peer-review

45 Citations (Scopus)


A successful response to the COVID-19 pandemic requires achieving high levels of vaccine uptake. We tested whether directly contrasting the high efficacy of COVID-19 vaccines with the lower efficacy of the annual flu vaccine would increase intentions to take a COVID-19 vaccine.
A pre-registered online study of 481 participants compared four information conditions: a) No Information, b) COVID-19 Vaccine Information Only, and COVID-19 Vaccine Information combined with Flu Vaccine Information suggesting either c) 60% efficacy or d) 40% efficacy; we measured COVID-19 and flu vaccine intentions along with several other vaccine-related variables.
The Prolific platform was used to recruit 481 UK participants (64% female; aged between 18 and 85 years) who had been pre-screened to have intermediate levels of vaccine hesitancy. After reading a short text (~200 words) about COVID-19 vaccines participants were asked about their vaccination intentions.
Providing information about the safety and efficacy of the new COVID-19 vaccines resulted in vaccination intentions that were, on average, 0.39 standard deviations higher than those in the No Information condition; providing the same COVID vaccine efficacy information in the context of information about flu vaccine efficacy resulted in a further significant increase in vaccination intentions that were 0.68 standard deviations higher than those in the No-Information condition. This positive contrast effect for the COVID-19 vaccine was not associated with reduced flu vaccine intentions. Conclusions
Vaccination intentions can be strengthened through a simple messaging intervention that utilises context effects to increase perceived response efficacy.
Original languageEnglish
JournalBritish Journal of Health Psychology
Early online date11 Jul 2021
Publication statusPublished - 11 Jul 2021

Bibliographical note

Funding Information:
We thank Corwin Bainbridge for his assistance with research coordination, and the Wellcome Trust who funded this research via a grant awarded to Rubber Republic to work on COVID‐19 vaccine messaging to health professionals and communicators.

Publisher Copyright:
© 2021 The Authors. British Journal of Health Psychology published by John Wiley & Sons Ltd on behalf of British Psychological Society.

Structured keywords

  • Covid19


  • COVID-19
  • vaccines
  • efficacy
  • health communication
  • psychological interventions
  • protection motivation theory


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