Although immunization is one of the great public health achievements, continued success depends on an available supply of the vaccines that are recommended for routine use. Beginning in 2000, the United States experienced vaccine supply disruptions of unprecedented scope and magnitude. Although most of the supply disruptions have been resolved, it appears that a fragile vaccine supply will be part of the immunization environment in the United States for the foreseeable future. Here, we describe the perspective of the Centers for Disease Control and Prevention on the recent supply disruptions and the methods used to manage vaccine shortages. The present article focuses on routine pediatric vaccines, including influenza virus vaccine.