Study variables
The randomization unit was a municipal administrative area known as the canton. Among the 19 cantons in the Ardennes region, participants were pooled out of 10 cantons that were randomly selected to constitute the intervention group (INT) and of nine cantons that made up the control group (CON). The choice of the canton as the randomization unit made it possible to limit contamination bias.Participants (aged 25 in 2020) in the INT group received information regarding the dTcaP booster vaccine (Fig. 
Information of the awareness campaign for the dTcaP booster vaccine disseminated by the French national health insurance to French adults aged 25 years (intervention group) residing in the Ardennes region on June 1, 2021