Vaccination is a simple, safe, and effective way to protect people against harmful diseases before they come into contact with them. It uses your body’s natural defenses to build resistance to specific infections and strengthens your immune system.

Vaccines train your immune system to create antibodies, just as it does when you are exposed to a disease. However, because vaccines contain only dead or weakened forms of germs such as viruses or bacteria, they do not cause disease or put you at risk for complications.

Most vaccines are given by injection, but some are given orally, (by mouth,) or sprayed into the nose.

Source: WHO