With normal aging the immune system tends to decline in response to decreased levels of defence mechanisms. The main changes that occur over time to the immune system are associated with decreased responses from lymphocytes to various antigens and the prolongated hypersensitivity (James & Levy, 2009). Over the time, the immune system tends to develop sensitivity to many different environmental factors and the adaptations to an individual’s lifestyle. Such changes involve, changes in the diet, stress levels are regulated, less exercise and higher risks of developing diseases, making the immune system adapt to a harder lifestyle (Gallorini et al, 2009).
Figure: Showing the different enviromental factors that affect immune reponses with nornal aging.

Common changes to the immune system with aging are:
  • Increasing dysfunction of the immune system.
  • Reduction in the production of both IgA and leukocytes.
  • The responses to the immune system by antibodies to antigens are significantly decreased.
  • More susceptible at developing infections that may lead to diseases.
  • The host defence slows day, making it harder to build up immune responses even with vaccinations.
  • Decrease in the function of T-lymphocytes and B-lymphocytes with aging.

Vaccine Development: Vaccine ImmunogenicityNeonatal Immune System : Adolescent Immune SystemReferences Contributed by Rana Hammoud