Immunization is the process whereby a person is made immune or resistant to an infectious disease, typically by the administration of a vaccine. Vaccines stimulate the body’s own immune system to protect the person against subsequent infection or disease. Immunization prevents diseases, disabilities, and deaths from vaccine-preventable diseases (VPDs), such as cervical cancer, diphtheria, hepatitis B, measles, mumps, whooping cough, pneumonia, poliomyelitis, diarrhoeal diseases by rotavirus, rubella, and tetanus.
It is estimated that if coverage targets are met for the introduction and/or continued use of only 10 vaccines (against hepatitis B, Haemophilus influenzae type b, human papillomavirus, Japanese encephalitis, measles, meningococcus A, pneumococcus, rotavirus, rubella, and yellow fever) between 24 and 26 million future deaths in 94 low- or middle-income countries in the decade 2011-2020 could be prevented.
For over 40 years, the success of the Expanded Program on Immunization (EPI) has made the Region of the Americas a global leader in the elimination and control of vaccine-preventable diseases (VPDs), such as smallpox, polio, rubella, congenital rubella syndrome, measles, and neonatal tetanus. Since the creation of the EPI in 1977, countries have moved from using six vaccines in their national vaccination schemes, to an average of more than 16 vaccines, which represents greater protection for the population.