 Vaccination in a population results in herd immunity and greatly improved population health, with significant reductions in viral infection and disease.Vaccination policy in the United States consists of public and private vaccination requirements.For instance, public schools require students to receive vaccinations (termed "vaccination schedule") for viruses and bacteria such as diphtheria, pertussis, and tetanus (DTaP), measles, mumps, rubella (MMR), varicella (chickenpox), hepatitis B, rotavirus, polio, and more.