I was asked to answer this on Quora, an informational web site.
What is the difference between cold, flu, and fever?
There are many viruses, and still more to be discovered. The most common viruses that produce the "common cold" are:
- Rhinoviruses -- causing 10% to 40% of colds
- Coronaviruses -- causing 20% of colds
- Respiratory syncytial virus (RSV) -- responsible for 10% of cold
Dr Bollmann on Bare Skin Care
I advise everyone to get a flu shot (influenza vaccine) every year, since influenza can be a severe and disabling illness, producing a pneumonia that might cause death, esp in the young and the elderly. I strongly advise this because of a personal experience - I had influenza that lasted six weeks.
Although many people say they have the "flu", most just mean they have the common cold.
Fever is merely an increase in body temperature above the normal 98.6 degrees.
A significant fever in an adult is 101 degrees, and very significant if 104 in an adult. Children often run high fevers.