The Immunisation Beliefs and Intentions Measure (IBIM): predicting parents' intentions to immunise preschool children.

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.