Define: mystery
something that people can't understand or explain
Define: Immune System
parts of your body that work together to fight disease
Define: virus
a tiny living thing that causes diseases
Define: overwhelm
to take over something and something to stop working
Define: avoid
to stay away from a person or thing
Define: symptom
something wrong with your body that shows you are sick
Define: exposed
to be put in a situation that is dangerous or uncomfortable
Define: Contain
to have or hold something.
Define: vaccine
a substance used to keep people from getting a disease
Define: Protect
to keep a person or an item safe from harm or illness
Define: Infect
to make some sick
Define: spread
to move and a affect a larger area