They are proteins that synthesize our immune system to defend against bacteria, viruses, fungi… and other parasites that infect our body.
Antibodies are generally formed by cells of the blood, and are called B lymphocytes.
All the antibodies generated recognize a specific protein of these organisms that invade us. The antibody recognizes protein is called an antigen.
The vaccines help our body produce antibodies against a specific microorganism.
To this end the vaccine contains antigens that microorganism when injected into our body B lymphocytes generate antibodies against these antigens, and thus are ready to repel an infection when the microorganism invades the body.