People who suffer from diarrhea are vulnerable to dehydration. The role of antibodies Our bodies are designed to fight off disease. Our immune systems can identify pathogens, then make antibodies to attack them. We are then immune to that disease. When we get sick, it is usually because the pathogen is unfamiliar to our immune system and is present in such numbers that the body can't make antibodies quickly enough to prevent infection.
Most vaccines prevent disease by introducing materials that trigger antibody formation.