Question

What is a vaccine? How does immunity develop against a disease, when vaccine for those diseases is introduced in the human body?

Answer 1

Vaccination is the process of giving the vaccine. Many diseases, particularly infectious diseases like smallpox and chickenpox, have been eradicated because of it. The word "vaccine" comes from the Latin word "vaccinus", which comes from the word "vacca", which means "from cows.
The phrases vaccine and vaccination are derived from Variolae vaccinae (cowpox), a name coined by Edward Jenner (who invented the first vaccine as well as the concept of vaccines) to describe cowpox.

Complete answer:
A vaccination is a biological preparation designed to provide acquired immunity against a specific disease. Vaccines usually contain a weakened or dead version of the disease-causing pathogen, as well as its surface proteins and toxins. The immune system is able to recognize and kill the threat when this preparation is put into the human body.
The human body contains a variety of defence mechanisms against infections (disease-causing organisms). The skin, mucus, and cilia all function as physical barriers to keep germs out of the body in the first place.
When a pathogen infects our bodies, our bodies' defences, known as the immune system, are activated, and the infection is attacked, eliminated, or overcome.
When the body makes antibodies in response to an antigen, it also forms antibody-producing memory cells, which continue on even after the pathogen has been vanquished by the antibodies.

Note:
Vaccines are the best defence against a fatal disease that is both avoidable and spread. Vaccines are one of the safest medical medicines on the market, but there are some precautions to take. People can make vaccine decisions with more precision when they have more information about the benefits of immunizations as well as their potential negative effects.