Vaccination myth

There is a whole debate about vaccines throughout the year. Some people believe that vaccines are not a natural thing, which must not be inserted into our bodies, as they cause more harm than benefit.

The truth is in contrast to the belief. Our body is protected by immune cells. These cells act upon foreign bodies and eliminate them, as they can make us feel sick. The immune cells work by recognising the antigen on the surface of pathogens and producing antibodies to kill them.

Our body has innate immunity and adaptive immunity. In simpler words, innate immunity is the body's first and immediate line of defence against pathogens, providing a non-specific defence that acts within minutes to hours. The innate immune system reacts in the same way to any invader it recognises as foreign, without differentiating between specific pathogens. The skin, mucous membranes, tears, saliva, and stomach acid physically block or chemically neutralise pathogens. Unlike the adaptive immune system, the innate system does not "remember" past infections. It responds to the same pathogen in the same way every time.

A specialised component of the immune system, the adaptive immune system—also known as acquired immunity—specifically targets infections and offers enduring protection via memory. It arises during germ exposure and depends on B cells and T cells to recognise particular antigens, generating immunological memory cells and targeted antibodies for protection in the future. Although this system reacts more slowly than the innate immune system, it is more specialised and retains information about previous infections, which results in a stronger and quicker reaction when exposed again.

When the innate immune system can't eliminate a pathogen, APCs present fragments (antigens) of the germ to T and B cells. This presentation activates B and T cells that are specific to that particular antigen. Activated B cells produce large amounts of antibodies, which are specialised to target the specific pathogen. Cytotoxic T cells, a type of T cell, hunt down and destroy infected cells. The immune system "remembers" the pathogen by creating long-lived memory cells. On a second encounter, these memory cells quickly initiate a rapid and powerful response.

This is how a vaccine works. By simulating a genuine infection without causing severe sickness, vaccines strengthen the immune system and "train" it to identify and swiftly combat a particular pathogen should it reappear in the future. In this phase, a memory of the germ is created, and certain immune cells are activated.

Antigens are introduced into the body through vaccinations. These antigens can be genetic material (mRNA or DNA) that directs the body's cells to create the antigen, weakened or deceased strains of a virus or bacteria, or a tiny portion of the germ (such as a protein component). The immune system recognises these antigens as alien intruders and responds accordingly. Antigens are swallowed and digested by immune cells such as macrophages, which then present parts of them to other immune cells. B-lymphocytes are prompted to create antibodies, which are specialised proteins that bind to certain antigens and identify the pathogen for destruction. The development of long-lasting memory B and T cells is an important step in this process. These "memory" cells linger in the body for years or even a lifetime, "remembering" how to fight that particular infection. If the body is exposed to the genuine, harmful infection in the future, the memory cells are prepared to respond quickly and massively. They quickly develop the appropriate antibodies and trigger other immune responses to eliminate the invader before it can cause disease or serious problems.

In essence, a vaccine provides a safe "practice run" for the immune system, allowing it to develop a robust defence without the risks associated with a first-time encounter with a dangerous disease. This not only protects the individual, but it also helps to build herd immunity, which protects vulnerable populations that cannot be vaccinated.