Full Answer
Often, when people age, there is immunosenescence, which means that the immune system doesn't function as well or as vigorously. The combination of increased comorbid conditions and the decrease in activity of the immune system can make people more prone to infections.
Physiological processes like inflammation, environmental exposure to pollutants and radiation (like ultraviolet radiation from the sun), the effects of lifestyle factors like smoking, diet and fitness levels, as well as simple wear and tear, can all accelerate the rate of decline in different people.
Older patients are more susceptible to infections because their immune systems are weaker. They also may have additional conditions that open the door for infection. Chronic age-related diseases can contribute to weakness as well.
The appearance of many well-recognized "diseases of aging" tends to mask a similar rise in the susceptibility of the aged to infections. The immune response, particularly cell-mediated immunity, declines in efficiency with age, but this change alone does not explain the increased occurrence of infections.
With age, bones tend to shrink in size and density, weakening them and making them more susceptible to fracture. You might even become a bit shorter. Muscles generally lose strength, endurance and flexibility — factors that can affect your coordination, stability and balance.
Ageing is associated with a progressive degeneration of the tissues, which has a negative impact on the structure and function of vital organs and is among the most important known risk factors for most chronic diseases.
The effects of aging on the immune system are manifest at multiple levels that include reduced production of B and T cells in bone marrow and thymus and diminished function of mature lymphocytes in secondary lymphoid tissues. As a result, elderly individuals do not respond to immune challenge as robustly as the young.
Don't respond as well to vaccines: Your immune system includes T cells, which attack other, illness-causing cells. They're able to “remember” an invader, then defend against it better later. When you're older, you make fewer T cells, and most vaccines require new ones to work.
A susceptible person is someone who is not vaccinated or otherwise immune, or a person with a weakened immune system who has a way for the germs to enter the body. For an infection to occur, germs must enter a susceptible person's body and invade tissues, multiply, and cause a reaction.
As a person ages, the ability of the immune system to differentiate between invaders and normal tissues diminishes. 2. With increasing age, the immune system is no longer able to defend the body from foreign invaders, and detrimental changes result.
Aging is associated with a reduced capability of the immune system to adequately respond to pathogens and to prevent tumor formation. As a consequence of immunosenescence, older people have a higher risk to develop infections as well as cancer.