Why doesn't a disease come back once it's been contracted? Let's talk about Natural Immunity!

Do you remember when you got chickenpox as a child, your parents would say, "You'll never get it again"? Or you might have heard that someone who has had measles will never get it again. There's actually a lot of truth in that story. Our bodies fight diseases and after winning that battle, they retain a memory of that disease. That's what we simply call natural immunity . It's like having a superhero inside our bodies. Today, we'll talk about this superhero in a simple way that you can understand.

Simply put, what is this natural immunity?

Imagine that our body is like a big fortress. Outside this fortress, enemies (i.e., viruses, bacteria, etc.) are waiting to attack. If one enemy somehow gets inside this fortress, i.e., if we get sick, the army in our body, i.e., the immune system , gets ready for battle.

This army is very clever. They are making special weapons to destroy this enemy. We call these weapons antibodies . These antibodies go and fight those germs, destroy them and make us healthy.

But the story doesn't end there. The real story begins there.

After this battle is over, a special group of soldiers in our immune system, called memory cells , remember the shape of the previous enemy, all its details. They act like they take a photo of the enemy and keep it. Scientifically speaking, they remember a specific mark on that germ. It's called an antigen .

These memory cells continue to patrol our bodies even after we recover from the illness. Their only job is to watch for the old enemy to come back. So, if one day the same old germ tries to enter our bodies again, these memory cells recognize it as soon as they see it and shout to the whole army, "The old enemy is back!" Then our immune system makes antibodies faster and more powerful than ever before, destroying the germ before it can cause us any illness. Most of the time, we don't even notice it.

So you see, natural immunity is not something that is just given. It is acquired by our bodies through fighting an illness, overcoming it, and remembering that experience .

The two main lines of defense in our immune system

Our body's defense system, the immune system, can be divided into two main parts. It's like two rings of defense.

Most people refer to this second type of immunity as "natural immunity" because it is what creates a memory that is specific to that disease after it develops.

Two other aspects of natural immunity

This natural immunity can be further divided into two parts depending on how we acquire it.

1. Natural Active Immunity

This is what we've been talking about for so long. "Active" means that our bodies actively work to build this immunity. That is, when we get sick, our own immune system works hard, makes antibodies and memory cells, and builds that immunity. It's like we work hard to make money.

2. Natural Passive Immunity

"Passive" means that our bodies don't work hard to build immunity here. Instead, it's a gift to us.The best example of this is the immunity a child receives from a mother.

• During pregnancy: Many of the antibodies in the mother's body are passed to the baby through the placenta.
• After birth: If you are breastfeeding, your baby will also receive valuable antibodies through breast milk.

The immunity gained in this way will help protect the baby from diseases until his own immune system is well developed. But this is temporary. It's like borrowing money from someone. After a while, those antibodies will disappear.

How long does this natural immunity last?

This varies depending on the disease and may also vary depending on your physical health.

• Lifelong immunity: There are some diseases that, once you have had them, you will never get them again. Examples include measles and hepatitis A.
• Short-term immunity: There are other diseases for which the natural immunity is only short-lived. This is why we get diseases like the common cold , influenza (flu) , and COVID-19 multiple times in our lives.

Why is that? Because these viruses are very cunning. They constantly change their appearance (mutate). Then our memory cells cannot recognize them. Just like a thief who grows a beard and hair and comes in a different disguise is difficult to recognize.

Natural immunity or vaccination? Which is better?

This is a question that many people have. Both natural immunity and vaccine-derived immunity are a type of "active immunity." That is, in both cases, our bodies produce antibodies and memory cells. But the reason for this is different.

When a large number of people in a society become naturally or through vaccinations immune to a disease, the spread of that disease stops. We call this herd immunity . The safest and best way to achieve this is through vaccination.

Let's talk specifically about COVID-19 and natural immunity

With the COVID-19 pandemic, many people started talking about this natural immunity. There are those who think, "I had COVID, now I won't get it again." But as doctors, we absolutely do not endorse relying solely on natural immunity for COVID-19. There are several reasons for that.

• COVID-19 is an unpredictable disease: No one can predict exactly how this virus will affect someone. For some, it may feel like a mild cold, while for others it can lead to severe pneumonia, hospitalization, and even death. There are also complications that can last for months or years, such as long-term COVID . So it makes no sense to take such a risk and wait for immunity.
• The virus is constantly changing: You may remember the Covid variants like Delta and Omicron. When the virus mutates like this, the natural immunity you get from one variant may not protect you from another. But vaccines are constantly being updated to accommodate new variants.
• Risk of autoimmune diseases: Some research has found that when we get COVID-19, our bodies produce autoantibodies.These are antibodies that attack our own healthy cells. This poses a risk of developing autoimmune diseases. Research has not confirmed a link between vaccination and these types of autoantibodies.

Therefore, even if you have had COVID-19 before, the safest thing to do is to talk to your doctor and get vaccinated. The vaccine can give you strong immunity without the risk of severe illness, hospitalization, or death.