Advertisements promoting human papillomavirus vaccine for adolescent boys: does source matter?
- 1Department of Health Behavior and Health Education, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, USA
- 2Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina, USA
- 3Division of Cancer Prevention and Control, College of Medicine, The Ohio State University, Ohio, USA
- 4Comprehensive Cancer Center, The Ohio State University, Ohio, USA
- Correspondence to Dr Noel T Brewer, UNC Gillings School of Global Public Health, Department of Health Behavior and Health Education, 325 Rosenau Hall, CB 7440, Chapel Hill, NC 27599-7440, USA;
Contributors JKP, PLR, A-LM and NTB all participated in the development of the survey and data analysis. JKP drafted the initial manuscript. The other co-authors provided significant input on all subsequent revisions. All authors had full access to all of the data in the study and can take responsibility for the integrity of that data and the accuracy of the data analysis.
- Accepted 4 December 2011
- Published Online First 4 January 2012
Objectives Many parents recall hearing of human papillomavirus (HPV) vaccine through drug company advertisements. This study sought to examine whether parents accurately recall the source (ie, sponsor) of advertisements promoting HPV vaccine and the impact of drug company advertisements.
Methods A US national sample of 544 parents of adolescent boys aged 11–17 participated in an online between-subjects experiment. Parents viewed an advertisement encouraging HPV vaccination for boys with a logo from a randomly assigned source. Parents rated trust, likability and motivation for vaccination while viewing the advertisement and later indicated who they believed sponsored it.
Results Nearly half (43%) of parents who viewed a hypothetical advertisement containing a logo incorrectly identified the advertisement source. More parents correctly identified the source of drug company advertisements than advertisement from other sources (62% vs 25%, OR 4.93, 95% CI 3.26 to 7.46). The majority of parents who saw a logo-free advertisement believed a drug company created it (60%). Among parents who correctly identified the advertisement source, drug company advertisements decreased motivation to vaccinate their sons, an association mediated by reduced liking of and trust in the advertisements.
Conclusions Parents were more accurate in identifying drug company advertisements, primarily because they tended to assume any advertisement was from a drug company. Public health organisations may need to take special measures to ensure their messages are not perceived as sponsored by drug companies.
- cervical neoplasia
- drug company
- HPV vaccine
- public health
- sexual health
- social science
- vaccination influenza
Human papillomavirus (HPV) vaccine can prevent several cancers and genital warts.1 2 Guidelines recommend routine vaccination of boys,3 although uptake is very low.4 Many parents recall hearing of HPV vaccine through drug company advertisements,5 which may be problematic as people find corporate sources less credible than non-profit or government sources,6 and credibility can affect intentions and behaviour.6 7 It is thus possible that parents have negative reactions to drug company advertisements that hinder vaccine uptake. We hypothesised that parent accuracy in identifying the source would only be moderate because extensive advertising of HPV vaccine by drug companies would make them the presumed source, and advertisements from drug companies would be less liked and trusted and therefore less likely to motivate parents to vaccinate their sons.
Parents, who were in a survey panel and had at least one son aged 11–17 years, received an email invitation to participate in our online survey in autumn 2010.8 The survey company developed the panel from a probability-based sample of US households. Of 1195 parents invited to participate, 752 responded to the invitation, and of those 72% (n=544) were eligible and completed the survey. The demographic characteristics of respondents appear elsewhere.4 The Institutional Review Board at the University of North Carolina approved the study.
We randomly assigned parents to one of 10 conditions in a 5 (source of ad) × 2 (warning text) between-subjects factorial experiment. They viewed a display advertisement (see supplementary appendix 1, available online only), encouraging them to vaccinate their sons, with a randomly assigned logo that indicated source: (1) Merck; (2) Gardasil; (3) Centers for Disease Control and Prevention (CDC); (4) American Cancer Society (ACS); or (5) no logo. We chose the CDC and ACS because they are credible alternative sources for information on HPV vaccine with widely disseminated logos. There was no effect of an additional manipulation (the inclusion of safety information warning text), so we do not discuss it further.
While viewing the advertisement, parents rated their agreement with these statements on a four-point scale (strongly disagree (coded as 1) to strongly agree (4)): ‘I like this ad’; ‘I trust this ad’ and ‘This ad makes me want to vaccinate my son against HPV’. Once the advertisement was no longer on screen, parents indicated whether the advertisement's sponsor was a drug company, government agency, charity for cancer, or insurance company. We coded parents' responses as correct if they selected ‘drug company’ for advertisements with Merck or Gardasil logos; ‘government agency’ for advertisements with a CDC logo; or ‘charity for cancer’ for advertisements with an ACS logo. Other response combinations were incorrect.
Using logistic regression, we examined whether the actual advertisement source predicted advertisement source misattribution. These analyses did not include participants who viewed an advertisement without a logo because they could not, by definition, be correct about source.
We used linear regression to examine the effects of the perceived advertisement source (drug company vs not a drug company, coded as 1 and 0) on parents' ratings of likability, trust and motivation to vaccinate. This analysis excluded respondents who saw advertisements without logos or inaccurately identified the advertisement source, to eliminate those for whom the logo manipulation failed. We examined trust and likability as potential mediators.9 Analyses with SPSS version 17.0 used two-tailed statistical tests and a critical α of 0.05. βs denote standardised regression coefficients.
Nearly half (43%) of parents who viewed a hypothetical advertisement containing a logo incorrectly identified the advertisement source. More parents correctly identified the source of drug company advertisements than advertisements from other sources (62% vs 25%, OR 4.93, 95% CI 3.26 to 7.46). The majority of parents who saw the logo-free advertisement believed it was created by a drug company (60%).
Effect of source
Among parents who correctly identified the advertisement source (n=243), most agreed or strongly agreed that they liked the advertisement (69%) and trusted it (60%). Fewer (38%) agreed or strongly agreed that the advertisement made them want to get their sons HPV vaccine. Parents who correctly identified drug company advertisements reported lower levels of liking, trust, and motivation to vaccinate than those who correctly identified advertisements from another source (all p<0.05).
Greater liking of (β=0.46, p<0.001) and greater trust in the advertisement (β=0.31, p<0.001) both predicted greater motivation to vaccinate (figure 1), but the association between source and motivation became non-significant when controlling for liking and trust (β=−0.16, p=0.01 without controlling; β=−0.02, p=0.74 after controlling). This pattern suggests mediation: drug company advertisements elicited lower liking and trust and, in turn, lower liking and trust reduced motivation to vaccinate sons against HPV.
Drug company advertisements motivated parents less to vaccinate, relative to non-drug company advertisements, because parents liked and trusted the advertisements less. However, parents were more accurate in identifying advertisements from drug companies than other sources, primarily because they tended to assume any advertisement was from a drug company. Producing advertisements that are clearly not from drug companies could help public health organisations increase HPV vaccine uptake. Approaches could include providing a statement about the mission of the advertisement's sponsor or prominently displaying its contact information in the advertisement. Future studies should address the changing context of HPV vaccination. Parents' interest in HPV vaccine for their sons may rise now that guidelines recommend administering the vaccine routinely to boys.3 The relationship between the perceived source and attitudes towards vaccinating boys against HPV could change as parents see more HPV vaccine-related messages.
Study strengths include an experimental design and a national sample. One limitation is the self-reported vaccination intention outcome; however, intention is a key predictor of vaccine uptake.10 In addition, parents viewed the hypothetical vaccination advertisements as part of an experiment, not in a real-world context. Finally, although this study used a national sample, parents were from an online panel and mostly white and well-educated; generalisability should be established.
Ultimately, understanding links between advertisement sponsorship and parents' attitudes may help public health practitioners craft more effective promotion messages that parents could easily distinguish from ones by drug companies.
Funding This study was supported in part by a research grant from the investigator-initiated studies program of Merck Sharp and Dohme Corp. The opinions expressed in this paper are those of the authors and do not necessarily represent those of Merck Sharp and Dohme Corp. Additional support was provided by the American Cancer Society (MSRG-06-259-01-CPPB) and the Cancer Control Education Program at UNC Lineberger Comprehensive Cancer Center (R25 CA57726).
Competing interests A research grant to NTB and PLR from Merck Sharp and Dohme Corp funded the study. Merck Sharp and Dohme Corp played no role in the study design, planning, implementation, analysis, or reporting of the findings. NTB has also received grants and/or honoraria from GlaxoSmithKline and Merck Sharp and Dohme Corp. JKP, PLR, and A-LM have not received honoraria or consulting fees from these companies.
Ethics approval Ethics approval was granted by Institutional Review Board at the University of North Carolina.
Provenance and peer review Not commissioned; externally peer reviewed.