Attitudes, Risks and Norms: Understanding Parents' Measles-Mumps-Rubella (MMR) Immunisation Decision-Making

Abstract

Since Wakefield, Murch, Anthony, Linnell, Casson, Malik, Berelowitz, Dhillon, Thomson, Harvey, Valentine, Davies and Walker-Smith’s (1998) proposed a causal link between the MMR vaccine and autism and Crohn’s disease (a form of irritable bowel disease: IBD), vaccine uptake rates gradually declined in the UK. Parents of young children began to question the safety of MMR immunisation and were required to assess the risks and benefits of MMR immunisation during their decision-making process. The studies in the present thesis aimed to investigate factors influencing parents’ risk assessment, MMR intentions and behaviour to gain an understanding of parents’ decision-making process. A mixed method approach was taken, using both quantitative and qualitative methods. Four studies involving parents of young children and students were carried out in Scotland.

The first study was a cross-sectional questionnaire-based study which used Protection Motivation Theory (PMT) and Subjective Norm (SN) to understand parents’ MMR immunisation intentions and behaviour for first dose and second dose MMR vaccine. The results suggest PMT was a useful psychometric risk model when examining first-dose and second-dose MMR immunisation and associated risks. The inclusion of SN in the model increased its overall robustness. Differences between immunising parents and non-immunising parents were identified. Immunisers perceived measles, mumps and rubella to be severe diseases and reported greater susceptibility and fear in relation to the diseases, whereas non-immunisers reported more concern about the associated risks of autism and IBD. Additionally, immunisers were more likely to follow the advice of health professionals (GP and health visitor) and reported them to be important sources of information, whereas non-immunisers were less likely to follow advice from health professionals and reported the media and internet to be important sources of information.

The second study used a similar methodology to the first study but used PMT and SN to investigate MMR immunisation decision-making in a sample of 90 previously non-immunised university students during a mumps outbreak on campus. PMT and SN were found to be important constructs when understanding the students’ immunisation behaviour. In comparison with non-immunising students, immunising students reported greater fear, severity and perceived risks of the vaccine-preventable diseases. Non-immunisers perceived greater external barriers to immunisation and anxiety about immunisation to be an internal barrier. Both groups valued the information provided by health professionals and were more likely to follow the advice from these referents than any other referent group.

Comparisons were made between the results of the first two studies. The findings indicate PMT, including SN, was a useful model when examining the MMR decision-making process for immunisers and non-immunisers in different population groups. Parents and students reported similar threat appraisals in relation to the vaccine-preventable diseases, but were different in their coping responses (response efficacy and self-efficacy). Many similar patterns between students and parents were illustrated, but parents reported stronger beliefs related to their parental role. The results indicate that MMR decision-making differs depending on the population under study.

The third study used 5 focus groups and thematic analysis to explore the role of subjective norm (SN) and other social norms in greater depth with immunising parents. The findings indicate that social norms play a central role in the decision-making process, in addition to SN. Social normative factors which were found to contribute to the decision process included: group identification and norms, SN, descriptive norms, private self, relational self, and moral norms. The ‘private self’, i.e. own personal identity as ‘parents’, and feelings of moral obligation to their child were perceived as important social norms during the MMR decision. Parents were willing to listen to the advice of significant others but perceived their ‘private self’ as playing a more active role during the decision process. Experience of other parents’ MMR behaviour (descriptive norm) contributed to the risk assessment of the MMR vaccine and increased confidence in their own decision when congruent. The dual role of health professionals (who were also parents) as a ‘medical professional’ and as a ‘parent’ was influential during the decision process.

The final study further investigated the influence of health professionals (HPs) on parents’ MMR decision-making. The role of interpersonal and generalised trust was explored using one-to-one interviews with 6 MMR immunisers, 3 non-immunisers and 8 immunisers with single vaccines. All groups of parents reported generalised mistrust in the Government based on the provision of biased information and past experiences of Government behaviour. Parents who opted for the MMR vaccines described interpersonal trust with their own HPs, where HPs were willing to openly discuss concerns relating to the MMR vaccine. Parents opting for the single vaccines or refusing all vaccines tended to report mixed experiences with their HPs, with some parents citing them as unhelpful and unwilling to discuss MMR concerns. Greater trust was illustrated by all parents, regardless of immunisation status, for their own health professionals and the NHS than for private clinics offering the single vaccines. Parents opting for the single vaccines perceived them to be safer (in terms of autism and IBD) than the MMR vaccine but questioned their credibility.

The four studies illustrate that PMT facilitates understanding of parents’ MMR decision making and behaviour, and highlights the importance of including social norms (as well as important sources of information) and trust in future MMR immunisation research. Furthermore, comparisons with parents and students illustrate differences in coping appraisal between the two groups and suggest risk assessment differs depending on the saliency of the risk for the population group.