Direct and crowding-out effects of a Hepatitis B vaccination campaign.

We evaluate the direct and spillover causal effects of a Hepatitis B (HB) vaccination campaign in French schools on the vaccination adherence of the targeted pupils. Using a regression discontinuity design, we show that this campaign created an exogenous shock on vaccination behavior, increasing the HB vaccination rate for children aged 11 and above. At the same time, we show a drop in the measles, mumps, and rubella (MMR) vaccination rate of the targeted pupils and an increase in the parental belief that measles is a benign disease.