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Why Does Immunity Decrease With Age?

One of the main reasons people are extremely cautious when it comes to COVID-19 pandemic is to protect the elderly. Older people have weaker immunity, and if they get sick, it can lead to bigger problems. But why is that? Why does immunity decrease with age?

One of the main reasons people are extremely cautious when it comes to COVID-19 pandemic is to protect the elderly. Older people have weaker immunity, and if they get sick, it can lead to bigger problems. But why is that? Why does immunity decrease with age?

First, we should try to explain how the immune system works. The best way to describe it would be like a complex system made up of cells, organs, and tissues, all working in sync to provide protection to our bodies. The things they are defending the body from are various parasites, bacteria, germs, fungi, and many other things that are capable of causing infections and diseases.

What Are Antigens?

The term medical experts use to refer to the foreign things that invade our body is antigens. The most important cells that are a part of our immune system are leukocytes, more commonly referred to as the white blood cells. Immune systems can vary greatly from person to person. There is no way of telling how hard a disease will hit someone. Some people do not seem to feel a thing and are protected extremely well against all sorts of infections, while others just cannot catch a break and get the flu as soon as they exit the house.

As far as age goes, there are advantages and some disadvantages to our immune systems. Our bodies develop more and more defenses from antigens as we get older. Once we defeat a disease, our body creates antibodies that help us become more resistant to it in the future. This is the reason why adults do not get as many colds as kids do.

The Thymus And The T Cells

With age, our thymus is shrinking. What is a thymus, and why does this matter? Well, the thymus is a lymphoid organ of the immune system, located behind the breastbone. The thymus is the place where our white blood cells (leukocytes) grow and mature, and help us defend our body. These are not the only white blood cells our body has, but these are the most important ones, and they are called the T cells. 

he thymus is a lymphoid organ of the immune system, located behind the breastbone.
Thymus is a lymphoid organ of the immune system, located behind the breastbone.

T cells can have multiple functions. The most important ones are killing the antigens and coordinating all other parts of our immune system. With age, and the shrinkage of our thymus, their number does not decrease; however, their functions do. This is the main reason why our immunity decreases with age. This causes our immune system to lose strength, and the risk of becoming ill increases.

Another thing that happens with age is that macrophages do not work as rapidly as they used to when we were younger. Macrophages are another kind of white blood cells that have the function of ingesting antigens. This is presumably the main reason why older people get cancer more commonly. With the fewer number of white cells being able to react to all of the new antigens, the body cannot really “memorize” them, and it gets harder to create a defense system against it.

Other Ways Our Immunity Weakens With Age

These are basically the main reasons that make our immunity weaker as we get older. The antibodies are less in number, and their ability to attach themselves to the antigen and get rid of it slowly begins to weaken. All of these changes are the reason why pneumonia, influenza, and many other diseases like tetanus are more prevalent among our senior citizens. Another thing all of these changes can potentially influence is the effectiveness of vaccines. Vaccines are known to not be as effective with older people as they should be. 

The older people get, there are even more reasons their immunity begins to decrease. Sometimes, the immune system can become less receptive to the regular cells in the body. This is when autoimmune disorders can appear, such as lupus or scleroderma, to name a few. The elderly are also more likely to get diabetes, which also decreases their immunity. This is why it is crucial to protect the elderly during the coronavirus pandemic.

About the Author

Antonia is a sociologist and an anglicist by education, but a writer and a behavior enthusiast by inclination. If she's not writing, editing or reading, you can usually find her snuggling with her huge dog or being obsessed with a new true-crime podcast. She also has a (questionably) healthy appreciation for avocados and Seinfeld.

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