Jean Adams, Belinda Bateman, Frauke Becker, Tricia Cresswell, Darren Flynn, Rebekah McNaughton, Yemi Oluboyede, Shannon Robalino, Laura Ternent, Benjamin Gardner Sood, Susan Michie, Janet Shucksmith, Falko F Sniehotta, Sarah Wigham

Uptake of preschool vaccinations is less than optimal. Financial incentives and quasi-mandatory policies (restricting access to child care or educational settings to fully vaccinated children) have been used to increase uptake internationally, but not in the UK. To provide evidence on the effectiveness, acceptability and economic costs and consequences of parental financial incentives and quasi-mandatory schemes for increasing the uptake of preschool vaccinations. Systematic review, qualitative study and discrete choice experiment (DCE) with questionnaire. Community, health and education settings in England. Qualitative study - parents and carers of preschool children, health and educational professionals. DCE - parents and carers of preschool children identified as 'at high risk' and 'not at high risk' of incompletely vaccinating their children. Qualitative study - focus groups and individual interviews. DCE - online questionnaire. The review included studies exploring the effectiveness, acceptability or economic costs and consequences of interventions that offered contingent rewards or penalties with real material value for preschool vaccinations, or quasi-mandatory schemes that restricted access to 'universal' services, compared with usual care or no intervention. Electronic database, reference and citation searches were conducted. Systematic review - there was insufficient evidence to conclude that the interventions considered are effective. There was some evidence that the quasi-mandatory interventions were acceptable. There was insufficient evidence to draw conclusions on economic costs and consequences. Qualitative study - there was little appetite for parental financial incentives. Quasi-mandatory schemes were more acceptable. Optimising current services was consistently preferred to the interventions proposed. DCE and questionnaire - universal parental financial incentives were preferred to quasi-mandatory interventions, which were preferred to targeted incentives. Those reporting that they would need an incentive to vaccinate their children completely required around £110. Those who did not felt that the maximum acceptable incentive was around £70. Systematic review - a number of relevant studies were excluded as they did not meet the study design inclusion criteria. Qualitative study - few partially and non-vaccinating parents were recruited. DCE and questionnaire - data were from a convenience sample. There is little current evidence on the effectiveness or economic costs and consequences of parental financial incentives and quasi-mandatory interventions for preschool vaccinations. Universal incentives are likely to be more acceptable than targeted ones. Preferences concerning incentives versus quasi-mandatory interventions may depend on the context in which these are elicited. Further evidence is required on (i) the effectiveness and optimal configuration of parental financial incentive and quasi-mandatory interventions for preschool vaccinations - if effectiveness is confirmed, further evidence is required on how to communicate this to stakeholders and the impact on acceptability; and (ii) the acceptability of parental financial incentive and quasi-mandatory interventions for preschool vaccinations to members of the population who are not parents of preschool children or relevant health professionals. Further consideration should be given to (i) incorporating reasons for non-vaccination into new interventions for promoting vaccination uptake; and (ii) how existing services can be optimised. This study is registered as PROSPERO CRD42012003192. The National Institute for Health Research Health Technology Assessment programme.