Impact of a decision-aid tool on influenza vaccine coverage among HCW in two French hospitals: A cluster-randomized trial

Nosocomial outbreaks of seasonal influenza are frequent, and vaccination is largely recommended for healthcare workers (HCWs). Vaccine coverage in French HCWs does not exceed 20%. Decision-aids (DA) are potential useful interventions to increase vaccine coverage (VC). Our aim was to evaluate the impact of a DA on HCWs influenza vaccine coverage. Prospective cluster-randomized trial conducted in 83 departments in two public hospitals (a teaching and a non-teaching hospital) during the 2018–2019 flu season. Distribution of the DA and of questionnaire about decisional conflict and knowledge in the departments randomized in the intervention group. A total number of 3 547 HCWs were concerned by the study (1 953 in the intervention group, 1 594 in the control group). Global VC was 35.6% during the 2018–2019 season, instead of 23.6% in the 2017–2018 season (p < 0.005). During the 2018–2019 season, VC was 31% (95% CI 28.7–33.3) in the control group and 38.7% (95% CI 36.5–40.9) in the intervention group (p < 0.005). Among the 158 HCWs exposed to the DA who answered the survey, 51.3% had no decisional conflict. HCWs without decisional conflict were more prone to get vaccinated before flu season. The use of the DA was associated with a 25% relative increase in VC among HCWs against seasonal influenza. This modest increase remained far from the WHO 75% target, but may have reduced the number of nosocomial. Multi-component interventions are needed to increase VC in HCWs.