Randomised controlled trial of a theory-based intervention to prompt front-line staff to take up the seasonal influenza vaccine

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BMJ Quality and Safety


Objective To evaluate the effectiveness of reminder letters informed by social normative theory (a type of 'nudge theory') on uptake of seasonal influenza vaccination by front-line hospital staff. Design Individually randomised controlled trial. Setting A large acute care hospital in England. Participants Front-line staff employed by the hospital (n=7540) were randomly allocated to one of four reminder types in a factorial design. Interventions The standard letter included only general information directing the staff to take up the vaccine. A second letter highlighted a type of social norm based on peer comparisons. A third letter highlighted a type of social norm based on an appeal to authority. A fourth letter included a combination of the social norms. Main outcome measure The proportion of hospital staff vaccinated on-site. Results Vaccine coverage was 43% (812/1885) in the standard letter group, 43% (818/1885) in the descriptive norms group, 43% (814/1885) in the injunctive norms group and 43% (812/1885) in the combination group. There were no statistically significant effects of either norm or the interaction. The OR for the descriptive norms factor is 1.01 (0.89-1.15) in the absence of the injunctive norms factor and 1.00 (0.88-1.13) in its presence. The OR for the injunctive norms factor is 1.00 (0.88-1.14) in the absence of the descriptive norms factor and 0.99 (0.87-1.12) in its presence. Conclusions We find no evidence that the uptake of the seasonal influenza vaccination is affected by reminders using social norms to motivate uptake.

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