How Our Immune System Works?

en in humanity • 6 min read

Our immune system is a very complex and poorly understood mechanism. I had many wrong opinions about immunity, and I had a tough time understanding what was said about the ongoing pandemic and vaccination. I think this is the main reason for the wars between people these days. You know, I don’t want to be an extremist. Nothing is black and white. I think the openness to other ideas is the key for much needed toleration. But sometimes, there must be a clear red line beyond which it is forbidden to go. We cannot use our gut as an argument. It is OK to decide what to eat today or cook tomorrow. But when we talk about non-intuitive issues, let’s stick to logic and science.

The immune system is one such topic. Are you also hearing a lot about antigens and antibodies, and you have no idea what it means? What does antigen test or PCR test do? How our body reacts to pathogens, and why can you not be sick for a shorter period than seven days or a week? Are you on one side of the barrier, firmly believing in vaccination or against it, but you have no idea how it works, and why you believe in your belief?

In such a case, I strongly recommend reading a perfect book Immune: A Journey into the Mysterious System That Keeps You Alive by Philipp Dettmer, the founder and head writer of the fantastic science YouTube channel Kurzgesagt.

Honestly, I think this is the best book I read in 2021. Philipp makes sure to explain all necessary concepts very clearly. Complex parts are repeated with a slightly different approach to ensure the main principles are well understood. I was able to learn everything essential without the need to write notes! That’s quite impressive.

The whole book is also so wonderfully written! It is that good that I read every single footnote. First of all, they are fun; second, they are engaging; and lastly, they are as beautiful as the rest of the book. In a nutshell, it is one of the best science books I read. (OK. Maybe one footnote is unfortunate. That long one, probably the longest one, in a cancer chapter. The issue is not it is long, but I think it’s the weakest explanation from the whole book.)

Go read it and be impressed. You will never see the immune system the same way again; I will definitely not.

But yeah. It’s still a scientific book and quite a heavy read even though Philipp tries to simplify and avoid confusing and challenging naming as much as possible, but only up to a point it can be simplified. I can imagine this is not how you like to spend your free time.

In such a case, you can carry on with this post, at least, where I summarize my key take-aways. Keep in mind that the book is much better, more detailed, and correct. The following lines are my interpretation I decided to keep at hand anytime I think about immunity.


First of all, our immune system is perfect. It can deal with basically any pathogen from the past, any pathogen around us today, and any pathogen in the future. Really. But there is a catch. As with everything, we can buy anything we want, but we cannot buy time.

Time is the reason why you need to be sick or why you need to die due to some nasty virus. The immune system is excellent and powerful, yet it takes time to boot it up. You have defense cells for everything you can encounter. Of course, that must take a lot of space; therefore, you have a limited number of such cells against every possible pathogen.

When a pathogen enters your body, the first general defense is in the front line. This defense is not very direct and also kills your cells, causing inflammation. In the meantime, agents are scanning your whole body, taking samples, and looking for a specific warrior who can fight back. Once this warrior is found, it is duplicated—many times.

Detecting intrusion, finding warrior, and duplicating it takes time. It can vary, but that’s why the saying you cannot recover sooner than in a week or seven days exist. You need to lay down; there is no other way. Refusing to accept the illness means that your body doesn’t have enough energy for your immune system to be effective, and you will just prolong the unpleasant feelings or even die.

The first two days or so, the general fight is in progress, then a direct battle to get rid of the pathogen, and then a few more days to recover from the war. When the fight is over, our body cleverly keeps specialists against that pathogen in your body in huge numbers, so your body doesn’t have to fight the same war again in a few weeks. Because obviously, that is the virus appearing in your environment.

Here comes the trick with vaccines. Usually, we don’t need any boost because our immune system is truly remarkable. But sometimes, the virus can be too aggressive and kill you sooner than your immune system kicks in. Vaccines should gently say to your body to prepare the antibodies, so your immunity responds way faster when you encounter the virus in the wild.

I like the comparison from the book: it is like going to the fight course. You can go the natural way and fight with real weapons. Sometimes you will get hurt or even die, but you will be better prepared for natural conditions. Or you practice with foam weapons. You will sometimes be also hurt, but limiting to zero, yet you are ready enough for real-life as well.

There is this misunderstanding of what is actually the illness. It is not the headache, fever, runny nose, or even coughing. All this is the reaction of your immune system. When your body starts fighting the virus, it increases the body temperature. That makes life worse for viruses. And it is better for reproducing killer cells and spreading them to all fronts in your body.

Therefore, taking a pill to decrease temperature so we can ignore it and go to work is a terrible idea. First, it will not help your body; you will fight the pathogen for a more extended period. And second, you might make a sad weekend for your colleagues and people you meet on the way.

And therefore, vaccination causes such reactions as well. It is expected behavior. If this is not happening, your immune system is not working correctly. That also means it is good to plan when to take a shot in advance. Definitely, it is not good when you cannot slow down or when you are already fighting something else. Reproduction is also energy consumption heavy; that means it can affect your period or fetus. You have just a limited amount of energy for everything.

Another fascinating detail is that our skin is fantastic. It is difficult for the pathogen to enter your body through your skin. For sure, it can happen when you hurt yourself, and that’s why it is crucial to clean the wound properly. But there is another skin you don’t count as “your outside”: mucosa.

Basically, you have your outside wrapped in your inside. We all need to eat and breathe to get energy. And thus, somehow, the energy needs to get in. If we are covered entirely with our great skin, we won’t survive for long. So our body must be more tolerant against cells from outside. And that’s your digestive system.

It is super important to mind what we eat and breathe. There is much stuff in the air; bacteria, viruses, pores, but also pollution made by us—all that can potentially harm us.


It would be great if more people knew how our immune system works. I think the confusion is the root issue of extremists—both sides, anti-vaxxers, and anti-anti-vaxxers. And it is not the only problem that could be eradicated by understanding the immune system. We could be more mindful even during mild diseases and avoid spreading them to others. Can you imagine that face masks are not required, but all sick people wear them by default?








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