Our body is at a temperature between 35.8ºC and 37.2ºC. Sometimes, this temperature goes up. When it goes above 37.8ºC, we say that we have a fever.
A vaccine is a preparation that causes your body to produce antibodies which will make you immune to a disease. Antibodies? Immune?
Snot is a thick, gooey, sticky substance produced in some parts of our body. Poses no risk to your health, but it may be annoying.