Immunization and Moral Hazard: The HPV Vaccine and Uptake of Cancer Screening

Immunization can lead to moral hazard by reducing the cost of risky behaviors and reducing preventive efforts. In this study, we examine the effect of HPV (human papillomavirus) vaccination on participation in the Pap test, which is a diagnostic screening test to detect HPV and non-HPV-related cancerous processes. The HPV vaccination is explicitly recommended for women up to age 26 years who were not previously vaccinated. Pap tests are strongly recommended for women between 21 and 65 years old even after having the HPV vaccine. To study the effect of HPV vaccination on Pap test uptake, we construct a fuzzy regression discontinuity design, centered on the vaccination threshold age. The results suggest that moral hazard was not the dominant effect. The estimates show that women who have been vaccinated, if anything, are actually more likely to have a Pap test, possibly due to increased awareness of its benefits at the time of vaccination.