This TED Lesson lets us understand how cells work and how viruses act in our bodies. Each cell is like a whole country with a center, a powerplant, protective system, factories and so on.
When a virus enters a cell special enzymes surround that virus and feed off of it, killing the virus. We need to know that a virus is 1000 times smaller than a bacterium and a bacterium is 100 times smaller than a normal cell in our body. A virus is small, but it can multiply thousands of times in each cell and then spread out like crazy.
So, watch out. When you need to take the vaccine, simply take it and let your body be prepared for the fight.