A fever is abnormal rise in normal body temperature level.
In general, you are said to have fever when your body temperature is above 100.4ºF (38ºC). But this reading can vary slightly depending on how you take your temperature – oral (mouth), armpit, ear, forehead, or rectal.
Best way to take temperature: Armpit, ear, and forehead temperatures are easier to measure than rectal or oral temperatures, but they are very not as accurate.
A vaccine is a type of medicine that prepares the body’s immune system so that it can fight a disease, it has not come into contact with before. Vaccines are designed to prevent disease, rather than treat a disease once you have caught it. The flu vaccine can keep you from getting sick with the flu.
Flu vaccines cause antibodies to develop in the body about two weeks after vaccination. These antibodies provide protection against infection with the viruses that are in the vaccine.
The flu is an infection that is caused by viruses. The medical term for the flu is "influenza."
There are different type of flu, the most common type of flu is the "seasonal" flu. Besides seasonal flu, there is also the "swine" flu and the bird flu. Bird flu ("avian flu") is a severe form of the flu that is caused by a type of flu virus that first infected birds.