Elsevier

Vaccine

Volume 28, Issue 19, 26 April 2010, Pages 3350-3362
Vaccine

The Immunisation Beliefs and Intentions Measure (IBIM): Predicting parents’ intentions to immunise preschool children

https://doi.org/10.1016/j.vaccine.2010.02.083Get rights and content

Abstract

In England, uptake of the second dose of MMR (against measles, mumps, rubella), and dTaP/IPV or DTaP/IPV booster (against diphtheria, tetanus, pertussis, polio), is lower than that of the primary course. The Immunisation Beliefs and Intentions Measure (IBIM), based on the theory of planned behaviour (TPB) and qualitative interviews, was used to predict parents’ intentions to take preschoolers for these recommended vaccinations. Parents from 43 child groups in southern England were randomised to receiving questions about either MMR (N = 193) or dTaP/IPV (N = 159). Overall, 255 parents fully completed TPB-based items. Regression analyses revealed that parental attitudes about the protective benefits of immunising and perceived behavioural control were strong, reliable predictors of intention to immunise with MMR. For dTaP/IPV, perceived protective benefits and number of children reliably predicted intention to immunise. Differences between parents with ‘maximum immunisation intentions’ and those with ‘less than maximum intentions’ are described. The IBIM appears to be a useful measure for predicting parents’ intentions to immunise preschoolers. Implications for improving uptake are discussed.

Introduction

In the UK, preschoolers aged 3–5 years old are offered a second dose of measles, mumps and rubella (MMR) vaccine, and a booster against diphtheria, tetanus, pertussis and polio (dTaP/IPV or DTaP/IPV). The latest immunisation statistics for England indicate that uptake of these vaccinations continues to be lower than that of the primary course [1]. Despite this, only a limited number of studies [2], [3], [4], [5] have examined parents’ views about preschool immunisation and little is known about the beliefs that might best predict parents’ vaccination decisions.

Semi-structured interviews with parents of young infants [3] and parents of preschoolers [4] have identified uncertainty about the need for vaccinations at preschool age. Compared with primary immunisation, the parents of preschoolers reported receiving no information prior to their invitation to attend and had little or no contact with healthcare professionals at their general practice. Earlier interviews also found that parents typically reported receiving no information about the second MMR prior to immunisation and were unable to recall advice given when they had taken their child for the first dose aged 13–18 months [6].

In support, quantitative research has found that receipt of satisfactory information was significantly associated with MMR and pertussis immunisation among mothers of children aged 3 months to 6 years old in Italy [2]. In Australia, a study looking at interventions to increase uptake in school entrants found that the main reasons given for incomplete immunisation were lack of awareness that boosters were required and parental indifference, such as forgetting to attend [7]. In both studies, minor illness delayed parents from immunising on time.

Another body of evidence has used psychological theory to examine parents’ intentions to immunise. According to the Health Belief Model [8], protective health behaviours are partly a function of the perceived costs and benefits of performing the behaviour in question. Using this model, Bennett and Smith [9] examined the perceived benefits and costs of pertussis vaccination in parents who had fully vaccinated a child (n = 85), parents whose child had partially completed the course (n = 70), and parents who refused to vaccinate their child against pertussis (n = 73). They found that ‘refusing’ parents reported significantly more concern over long-term health problems as a result of vaccination, a lower risk of their child developing pertussis if not vaccinated, and attached a lower importance to vaccination than the other groups. Parental attitude was found to account for 18–22% of the variance in immunisation status.

Other studies have used the theory of planned behaviour (TPB) [10], [11], a well-known social cognition model, to predict parents’ intentions to immunise. According to the TPB, behaviour is determined by intention to engage in the behaviour and perceived control over performance of the behaviour. Intention is determined by a person's attitude towards that behaviour, subjective norms, and perceived behavioural control. In turn, attitudes are determined by the perceived consequences of performing the behaviour and the evaluations of these outcomes (behavioural beliefs). Subjective norms are determined by beliefs about whether others would want them to perform the behaviour and motivation to comply with these expectations (normative beliefs). Perceived control is determined by beliefs about factors that may facilitate or hinder performance of the behaviour and the perceived power of these factors (control beliefs). According to Ajzen [12], people with more positive attitudes and subjective norms and greater perceived control will have greater intentions to perform the behaviour.

Using the TPB, Pareek and Pattison [5] compared mothers’ intentions to take children for either the first or second dose of MMR. They found that mothers of preschoolers (approaching the second dose) had significantly lower intentions to immunise than mothers of young infants (approaching the first dose). For the mothers of young infants, intention was predicted solely by ‘vaccine outcome beliefs’: parents with stronger intentions to immunise had more positive beliefs about the outcomes of vaccination and the evaluation of these (accounting for 77.1% of the variance in intention). Stronger intentions to immunise with the second MMR, however, were predicted by positive parental attitudes, prior MMR status (whether or not they had attended for the first dose), and ‘vaccine outcome beliefs’ (accounting for 93% of the variance in intention). In the Netherlands, a computer-based survey conducted in 1999 found that high vaccination intention was influenced by beliefs that immunisation was safe and the best way to protect children against disease [13]. Parents with less than maximum intentions were more likely to believe that their child received too many vaccinations simultaneously and that vaccination interferes with the natural development of the immune system. In America, positive parental attitude and a strong sense of perceived control contributed to higher immunisation uptake by 2 years of age [14]. Subjective norm was found to exert no influence on immunisation and was excluded from the model.

In summary, whilst some research has explored parents’ views about preschool immunisation, this has been limited and largely qualitative. Moreover, although psychological theory has been applied successfully to the prediction of immunisation uptake, no published studies have used these models to predict parents’ intentions to immunise children under the current preschool immunisation programme in the UK. The development of a psychometrically valid and reliable measure for parents, based on a behaviour change model [15], is essential if we are to understand which parental beliefs need to be addressed in future interventions to improve immunisation uptake. Therefore, the aim of the present study was to use an interview-informed, TPB-based questionnaire to examine parents’ intentions to immunise preschoolers with either the second dose of MMR or dTaP/IPV. Of particular interest were any differences in how decisions were made for the two, of which only MMR has had a controversial history. It was hypothesised that there would be differences between parents’ beliefs and intentions to take preschoolers for MMR compared with dTaP/IPV. It is important to explore parental attitudes towards both vaccinations as they tend to be given at the same appointment and so concerns regarding one are likely to influence uptake of the other. Furthermore, by using quantitative evidence to determine the salience of beliefs expressed in qualitative interviews [3], [4], appropriate interventions can be developed in an attempt to improve immunisation uptake.

Section snippets

Design

In a cross-sectional design, parents were randomised to receiving an identical set of questions about taking their preschooler for either the second dose of MMR (MMR group) or dTaP/IPV (dTaP/IPV group).

Participants

Approval was obtained through the internal ethics committee of Royal Holloway, University of London. A total of 43 nurseries, playgroups and toddler groups in eight areas in southern England (Hampshire; Surrey; Middlesex; Buckinghamshire; Hertfordshire; London; Berkshire; Dorset) were invited to

Response rate

One hundred and ninety-three parents (189 mothers; four fathers) completed the MMR IBIM and 159 parents (147 mothers; 12 fathers) completed the dTaP/IPV IBIM. As the staff in each establishment distributed the questionnaires, the exact response rate is impossible to determine. For example, some distributed packs to all parents, whilst others left packs in the reception area for parents to take if interested.

Parent and preschool child characteristics

Examination of frequencies suggested missing data to be random. Thus, in accordance with

Discussion

This is the first study to use a questionnaire, based on qualitative interviews with parents [3], [4] and the TPB [10], [11], to predict and compare parents’ intentions to take preschoolers for either a second MMR or dTaP/IPV.

The prediction that there would be differences between the two vaccinations, both in the strength of the beliefs measured and in the extent to which they predicted parents’ intentions, was only partially supported. Generally, parents had positive attitudes towards

Conclusion

This study compared parents’ intentions to immunise preschoolers with either the second MMR or dTaP/IPV. Although there was no difference in parents’ immunisation intentions or in their scores on the other TPB components, significant predictors of intention differed. Furthermore, examination of the beliefs underlying these predictors revealed that there were differences in the extent to which these beliefs, generated from qualitative interviews with parents, were related to parents’ intentions.

Acknowledgements

The authors would like to thank Danielle Ashby, Kieley Hosier, Lissy Otto, Hannah Simpson and Clare Spray for assistance with data collection. Particular thanks go to the child group management and staff and the parents who participated.

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