A rise in vaccine hesitancy—a behavior influenced by lack of trust in the medical community, concerns about vaccine safety, efficacy, necessity or convenience and other issues related to vaccination—has contributed to undervaccination through parental decisions to delay or refuse vaccines for their children. A parent’s decision not to vaccinate his or her child puts not only that child, but every person that child comes into contact with at increased risk of infection. As more parents choose not to vaccinate, overall vaccination rates decline. Lower rates of vaccination increase the risk of preventable disease outbreaks by compromising herd immunity, a safe vaccination rate that can

signifi cantly reduce the spread of infectious disease within a community. Healthy People 2020—a national health promotion and disease prevention initiative of the U.S. Department of Health and Human Services (HHS)—established target vaccination rates for each vaccine-preventable disease that are necessary to achieve herd immunity and protect entire communities. Some childhood vaccines, such as measles, mumps and rubella (MMR), diphtheria, tetanus and pertussis (DTaP) and varicella (chicken pox), have a target vaccination rate of 95%, and many states and communities are failing to reach these goals. This PolicyLab Evidence to Action brief summarizes research findings around the causes and effects of vaccine hesitancy, and proposes policy changes that could lead to increased vaccination rates and greater protection for the current and future health of our children.