Anne-Laure Samson (Université de Lille)

We evaluate the impact of a French vaccination campaign against hepatitis B (HB) that took place in 1994. Using a regression discontinuity design, we show that this political measure created an exogenous shock on vaccination behaviors, increasing the vaccination rate against HB for children aged 11 and above. We also show that this vaccination scheme led to a decline in knowledge about the mode of transmission of the disease, confusion about the target population and, more importantly, a drop in measles, mumps, and rubella (MMR) vaccination rate. The effect on MMR vaccination was relatively unexpected and may imply a negative externality. Indeed, measles is an extremely contagious disease. If the vaccination rate falls, the disease will spread further, raising the question of the net effect of the HB vaccination campaign on the population well-being.