What is a vaccine?

A secondary school student gets vaccinated against TB as her younger sister looks on in this filepic. The BCG vaccine that protects against TB is a live-attenuated vaccine.

A vaccine is a substance that is capable of stimulating the production of antibodies in our bodies, in order to provide immunity against diseases.

Antibodies are proteins produced by our immune system to help defend our body against foreign invaders such as bacteria or viruses.