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摘 要：Vaccines have significantly contributed to worldwide reductions in morbidity and mortality by reducing the incidence of serious infectious diseases (IOM, 2012). Today, people all over the world experience the benefits of immunizations, beginning in infancy. Most adults in the United States have not witnessed firsthand the devastating illnesses against which vaccines offer protection, for example, polio, diphtheria, and Haemophilus influenzae meningitis. However, as the incidence of vaccine-preventable disease has declined, many do not appreciate the potential of these diseases to reemerge, and the potential adverse effects of the vaccines themselves take on greater saliency among certain stakeholders. Indeed, vaccine safety concerns exist among a diverse range of individuals, institutions, and formal and informal networks worldwide. Healthy individuals are immunized with immunogenic materials that induce immunity to serious pathogens. A schedule is a tool that is used to ensure that the recommended immunizations are provided to shield both children and adults from disease when they are the most vulnerable. In the United States, schedules recommended by the U.S. Advisory Committee on Immunization Practices (ACIP) (schedules for children from birth to age 6 years, children and adolescents ages 7 through 18 years, and adults) are based on the immunogenicity of vaccines and the burden and timing of disease (CDC, 2011a). Each schedule is designed and updated yearly on the basis of new evidence (see Appendix A). This report focuses on the vaccines that protect young children under age 6 years against 14 different pathogens because that time period is when multiple inoculations are given (see Appendix A).