What Is Immunization?

When you get sick, your body makes antibodies to fight the disease to help you get better. These antibodies stay in your body even after the disease is gone, and protect you from getting the same illness again. This is called immunity. However, you don’t have to get sick to develop immunity. You can gain immunity against disease through immunization.

Immunity through immunization

Immunization (or vaccination) protects people from disease by introducing a vaccine into the body that triggers an immune response, just as though you had been exposed to a disease naturally. The vaccine contains the same antigens or parts of antigens that cause the disease, but the antigens in vaccines are either killed or greatly weakened. Vaccines work because they trick your body into thinking it is being attacked by the actual disease.

Immunity through immunization happens without the consequence of being ill and without the risk of potential life-threatening complications from the disease. Once a person is immunized, specific immune cells called memory cells prevent re-infection when they encounter that disease again in the future. However, not all vaccines provide lifelong immunity. Vaccines such as the tetanus vaccine require booster doses every ten years for adults to maintain immunity.

Not just for children

At any age, vaccination provides the longest-lasting, most effective protection against disease. Vaccine-preventable diseases can be serious, and in some cases can cause life-threatening complications that can lead to hospitalization. This is especially a concern for infants and young children, who are particularly more vulnerable. Having children vaccinated on time is important and helps ensure that they receive the protection they need as early as possible to fight off diseases before they are exposed to them.

Immunization is important not only in childhood, but in adulthood as well, to help promote healthy aging. This is because childhood immunization does not provide lifelong immunity against some diseases such as tetanus (lockjaw) and diphtheria. Adults require helper, or booster, shots to maintain immunity. Adult vaccinations may also be recommended to protect against disease common in adulthood such as shingles.

Adults who were not adequately immunized as children may be at risk of infection from other vaccine-preventable diseases. They can also infect others. For example, adults who become ill with measles, mumps or pertussis (whooping cough) can infect infants who may not yet be fully immunized.

Since the introduction of vaccines, many serious illnesses have been brought under control.
Immunization can protect you from:

  • blood infection
  • diphtheria
  • ear infection
  • Haemophilus influenzae type b
  • hepatitis A
  • hepatitis B
  • Human papillomavirus (HPV)
  • influenza
  • measles (red measles)
  • meningitis
  • mumps
  • pertussis (whooping cough)
  • pneumonia
  • polio
  • rotavirus
  • rubella (German measles)
  • tetanus (lockjaw)
  • varicella (chickenpox)

Last Updated: 18 April 2019