title: Increasing the intent to receive a pandemic influenza vaccination: Testing the impact of theory-based messages.
abstract: Vaccination is an effective preventive measure to reduce influenza transmission, especially important in a pandemic. Despite the messages encouraging vaccination during the last pandemic, uptake remained low (37.6% in clinical risk groups). This study investigated the effect of different types of messages regarding length, content type, and framing on vaccination intention.
  
  
  
  An online experiment was conducted in February 2015. A representative sample of 1424 people living in England read a mock newspaper article about a novel influenza pandemic before being randomised to one of four conditions: standard Department of Health (DoH) (long message) and three brief theory-based messages - an abridged version of the standard DoH and two messages additionally targeting pandemic influenza severity and vaccination benefits (framed as risk-reducing or health-enhancing, respectively). Intention to be vaccinated and potential mediators were measured.
  
  
  
  The shortened DoH message increased vaccination intention more than the longer one, by increasing perceived susceptibility, anticipated regret and perceived message personal relevance while lowering perceived costs, despite the longer one being rated as slightly more credible. Intention to be vaccinated was not improved by adding information on severity and benefits, and the health-enhancing message was not more effective than the risk-reducing.
  
  
  
  A briefer message resulted in greater intention to be vaccinated, whereas emphasising the severity of pandemic influenza and the benefits of vaccination did not. Future campaigns should consider using brief theoretically-based messages, targeting knowledge about influenza and precautionary measures, perceived susceptibility to pandemic influenza, and the perceived efficacy and reduced costs of vaccination.
authors.affiliation: Research Department of Clinical, Educational and Health Psychology, University College London, WC1E 7HB, UK.
authors.forename: Cristina A
authors.initials: CA
authors.lastname: Godinho
authors.affiliation: Department of Psychology, Faculty of Social and Human Sciences, University of Southampton, UK.
authors.forename: Lucy
authors.initials: L
authors.lastname: Yardley
authors.affiliation: School of Health Sciences, Faculty of Health & Medical Sciences, University of Surrey, UK.
authors.forename: Afrodita
authors.initials: A
authors.lastname: Marcu
authors.affiliation: Department of Psychology, Faculty of Social and Human Sciences, University of Southampton, UK.
authors.forename: Fiona
authors.initials: F
authors.lastname: Mowbray
authors.affiliation: Research Department of Clinical, Educational and Health Psychology, University College London, WC1E 7HB, UK.
authors.forename: Emma
authors.initials: E
authors.lastname: Beard
authors.affiliation: Research Department of Clinical, Educational and Health Psychology, University College London, WC1E 7HB, UK. Electronic address: s.michie@ucl.ac.uk.
authors.forename: Susan
authors.initials: S
authors.lastname: Michie
mesh_terms: D004739:England; D005260:Female; D007722:Health Knowledge, Attitudes, Practice; D006293:Health Promotion; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology; D007252:Influenza Vaccines / Q000276:immunology; D007251:Influenza, Human / Q000517:prevention & control; D033182:Intention; D008297:Male; D008875:Middle Aged; D058873:Pandemics / Q000517:prevention & control*; D010342:Patient Acceptance of Health Care; D014611:Vaccination
chemical_list: D007252:Influenza Vaccines
keywords: Online experiment; Psychological predictors; Theory-based health messages; Vaccination uptake