Answer:
Antibodies
Step-by-step explanation:
The immune system works extremely hard to fight off the pathogen. Your body throughout the years of getting viruses and other things that make you sick, creates antibodies from the virus. It takes a little peice of the virus like a puzzle peice , so it can block it from coming into the body again. It does not always work as there are many stains of viruses and the body does not perform this perfectly.