How does vaccines provides immunity against infection, this question comes in almost every person’s mind, Because in today’s world vaccines are the easiest way to prevent any infection or to develop immunity against any disease.

Vaccines gives immunity

• History of vaccine

In 1796 Scientist Edward Jenner injected material from a cowpox virus into an eight year old boy with a hope that this would provide the protection needed to save people from deadly outbreak of the smallpox virus, and fortunately it was a success that eight year old boy was inoculated against the disease and this became the first ever vaccine.

To understand how vaccine provides immunity against infection first understand how "immune system defends us against contagious diseases"

When foreign microbes invades us the immune system triggers a series of responses in an attempt to identify and remove them from our body.

Like when disease germs enter in the body they starts to reproduce and your immune system recognise these germs as foreign invaders and responds by making protein called antibodies.

These antibodies first job is to help to destroy the germs that are making you sick (they can not act fast enough to prevent you from becoming sick , but by eliminating the attacking germs, antibodies help you to get well.

The second job of antibodies is to protect from future infections, they remain in your blood stream and if the same germ ever try to infect you again even after many years they will come to your defence.

Only now these antibodies are experienced at fighting to particular germs and can also able to destroy them before they have a chance to make you sick, this is innate immunity.

That’s why most people get disease like measles or chicken pox only once, even though they might be exposed many times during their life time.

The signs of this immune response is working are the coughing and fever that we experience, which work to trap, determine and rid the body of threatening things like bacteria, this is called innate immunity.

These innate immune responses also trigger our secondary line of defence [Adaptive immunity]. Special cells called B cells and T cells are present in our body to fight microbes and also to record information in them by creating a memory of what invaders look like and how to fight them.

This know-how becomes handy if the same pathogens invades the body again. But despite this smart response there is still risk in involved, because the body takes time to learn how to respond to pathogens and to build up the defences.

And even then if a body is too weak or young to fight back when it’s invaded , it might face very serious risk if the pathogen is particularly severe.

But what if we could prepare the body’s immune responses and make it ready before someone even got ill. Here is the point where the vaccine play an important role for providing immunity to us.

How does vaccine provides immunity against infection or diseases-:

Vaccine offer solution to the problem of getting sick and help us to develop immunity. To know how it works first understand what is vaccine and what its made from?

Vaccine:

Vaccine are made from the same germ [ or the part of them ] that causes disease, for example -: polio vaccine is made from polio virus, but the germs in vaccine is either killed or weakened so they don’t make you sick.

It ‘s a basically a biological preparation that provides active acquired immunity against particular disease. And typically it contains an agent that resembles a disease causing micro-organism.

That agent stimulates the body’s immune system to recognise the agent as threat and destroy it and keep a record of it, so that the immune system can more easily recognize and destroy any these micro- organisms that it can later encounter.

How vaccine provides immunity:

Vaccine provides immunity against infection

Vaccines are injected in the forms of antigens in to the body, once the antigen enter in the blood they circulates along with other cells such as B cells and T cells.

B cells and T cells are white blood cells that help the body to defend itself against foreign invaders, As the antigen invade the body’s tissue they attract the attention of macrophages.

Macrophages are non-specific scavengers which engulfs the antigens, these macrophages also signals the T cells that respond by attacking the invading antigen.

After vaccination the body will have a memory of an encounter with a potentially dangerous invaders, that’s how immunity develops against the particular pathogen in the body.