Vaccines open the way for mankind

Edward Jenner, who developed the world's first vaccine, inoculates his son. Painted by historian Ernest Board ⓒEEA picture library/GettyImages
Edward Jenner, who developed the world's first vaccine, inoculates his son. Painted by historian Ernest Board ⓒEEA picture library/GettyImages

Since the end of 2019, we have been living in an unprecedented era for more than a year and a half. It became difficult to meet close people, and family members abroad were able to check their safety only through the voice on the phone. The person I met on the job had to be remembered as wearing a mask. This year, vaccines (preventative drugs) began to spread, but the reality was different from what was expected. Time is still needed until the end of the damn chaos, and now new chaos is increasing with the vaccine itself. In addition to the difficult-to-understand viral infections, now you have to figure out which vaccine is better and which one is right for you. What is a vaccine and what are the bacteria and viruses that cause disease? Should we get the vaccine?

Immunity = the mystery of our body against pathogens

To understand vaccines, we first need to know about the substances that cause diseases in the human body, so-called pathogens. When a person is ill, it is sometimes expressed as infected, because infection means pathogens, that is, things that cause illness have entered the body. Excluding the accumulation of toxic substances, trauma due to accidents, genetic diseases, allergic diseases, etc., most of the cases where our bodies are sick and difficult are related to pathogens.

If you look up the definition of the word pathogen in the microbiology major book, it is defined as infectious disease is an infectious disease in which a part of the whole of the host's body is changed so that it cannot function normally due to parasites or their products. In simple terms, infection is when something other living things, or substances involved in life phenomena enter our body.

The human body has the function of responding to pathogens (antigens) that originally came from the outside. This is called immunity. Often, immunity is thought of as a power that needs to be charged (?) by administering drugs or injections, but it refers to a phenomenon in which our body defends against external factors.

In our body, several types of cells are involved in immunity, and each responds and defeats them according to the type of pathogen. There are countless microbes in the world, but most of us can live healthily thanks to this immune response. When an antigen comes in, a glycoprotein (a substance made by combining proteins and carbohydrates) is created in our body to fight it, and it is stored in blood and lymph, and then moves to the place where the body's immune response takes place to fight pathogens.

Then what are pathogens? It can be divided into four broad categories: bacteria and viruses, parasites (including some insects), and pathogenic fungi (fungi). In the modern era of improved hygiene, it is difficult to find diseases caused by parasites, and diseases caused by fungi are relatively well operated in our body's response system. However, it often appears as a skin disease (athlete's foot, etc.) that the body's immune system is difficult to access. In other words, in the modern world, most cases in which our bodies are infected and suffer greatly are not very wrong, even if they are considered to be caused by bacteria or viruses.

In the case of bacteria, many effective antibiotics have been developed, so treatment is not very difficult in modern times. Of course, there are still many deadly bacterial infections and, although very rarely, super bacteria...etc. have difficulty in treatment, in fact, it can be seen that diseases that occur through bacterial infection rarely do not have the drug itself. This is thanks to the advancement of medicine. Also, when vaccines such as typhoid fever, cholera, and whooping cough are already available, the vaccine is given in advance from an early age, so it is often lifetime prevention.

Why is a viral disease difficult to treat

On the contrary, viruses are still a problem in modern times, and there are many reasons, but first of all, because their size is too small. In the case of cells, they exist outside of human cells, and because they are large, it is difficult to enter the cells. It often stays in blood or body fluids outside the cell, and even if it accidentally enters the cell, it only enters the cell membrane and cannot invade the cell nucleus.

In contrast, the virus enters the cell. Rhinovirus, one of the representative cold viruses, is only 30 nanometers (nm) in size. 1nm is 1 billionth of a meter, and 30nm is only about 1300 millionths of a meter. Compared to most somatic cells, the size is as small as a few hundredths, and since it is three-dimensional, it is safe to say that the size is hundreds to tens of millions of times. When such a virus enters the body, it is settled in the cell, and inside the cell, it uses the cell as a factory and continuously replicates itself to produce it. And in the end, it kills even the cells, and the cloned virus again infects other cells around it, and the numbers continue to be called out.

So, isn't taking antiviral drugs like taking antibiotics cures a viral disease? It is possible to some extent, but this is also not that easy. Bacteria are definite living things that do life phenomena. So it was possible to make a drug that selectively kills only germs. However, viruses are genetic transmission materials that use human cells as factories, and they are too small to be killed because they are hidden in human cells.

Drugs that block the enzymes necessary for the process of replicating DNA by viruses to prevent synthesis are mainly used. This method prevents further reproduction and, in the end, requires the body's immune system to come out. Since it cannot be killed by selecting only the virus hidden in the cell, an immune cell called toxic T cell emerges and the virus responds by killing the infected cell itself. This is why, when the virus invades important tissues such as nerves, sequelae can often be seen even after treatment.

Immunity is a basic function that it has from birth. Anyone automatically responds to pathogens (antigens) from outside the body. Macrophages, such as white blood cells, attack pathogens, killing and destroying already infected cells. A reaction that creates an environment in which pathogens are easily washed away by generating fever and increasing the secretion of mucus is also a type of immunity.

These basic functions of the human body are sometimes not sufficient. In this case, the body of an infected person remembers the type of pathogen that entered the body by a specific cell called memory cell and rapidly produces various immune cells the body It responds effectively by making antibodies that respond to antigen (pathogen) Memory cells survive for several years in the short term and for a lifetime as long as it is. Vaccines are suitable preventive drugs to artificially create memory cells using these human functions.

The problem is some viral diseases. Some viruses, especially colds and similar respiratory viruses, are often mutated. In particular, mutations tend to occur very quickly in the case of infection by transmitting genetic material (RNA) rather than genetic material. 'Sascoronavirus', which causes Corona 19, is also in the same form, so it was difficult to develop a vaccine.

The first vaccine was pus from cattle, now a crystal of advanced genetic engineering

The first time the vaccine was launched was the well-known Edward Jenner. Jenner found out that the reason cows do not get smallpox is that they were exposed to smallpox similar to cowpox and suffered only weak symptoms in advance. did. In modern distinction, this corresponds to a subunit vaccine' that uses pathogens of similar diseases. In fact, the name vaccine itself comes from the Latin word Vacca for the cow. Later, by Louis Paster, who accepted Janer's method, a rabies vaccine, and a cholera vaccine were developed, followed by numerous researches and developments to now.

Various types and methods of vaccine have been developed so far. Live attenuated vaccines that use live pathogens as they are, dead vaccines that expect only immune responses using dead pathogens, and toxoid vaccines that extract only toxins from diseases have also appeared. Also, recently, a recombinant vaccine that extracts and injects only the part that responds to the antigen using the genetic information of the pathogen is widely used.

Then, how was the Corona 19 vaccine created? To cope with the Covid-19, which is so small and mutated, the method that pharmaceutical companies have found ways to aim for the protrusions attached to the virus. Coronavirus has an outer shell, and there is a protrusion made of a protein called peplomer around it, which is used to adsorb to human cells and invade by causing membrane fusion. The name Coronavirus is also given because this part looks like the flame of the Sun (corona).

This is why the word covid-19 spike protein' is often seen these days. By employing this principle, many of the Covid-19 vaccines respond to this form of Peplomeric to produce memory cells that can make antibodies. In this process, a gene transfer material was used, or technology was used to penetrate the cell and insert necessary information into the gene in the cell. Just as viruses manipulate cells to call their own tax, so vaccines are made to manipulate cells to produce antibodies.

Some people say, I'm still young, so it's not fatal even if I get coronavirus, and if I get healed by itself, I'm not afraid because I'm getting immunity.' However, it is difficult to guarantee how effective this acquired immunity is, and if only small mutations occur, you can get Covid-19 again at any time. It is much more advantageous to receive a vaccine for which the immune response is designed correctly according to the recommendations of the medical staff.

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