Answer:
They essentially first start with a small organism. This organism is then transferred to a host, usually transferred from eating/touching something. Then, the host gets infected with said virus.
The host will then pass on the organism by sneezing, coughing, and/or touching them. This continues on, usually until a cure is found. It can still have the ability to transfer, generally from people who don't get the cure.
Viruses can sometimes have a larger impact during different times.
Some people may also be more subject to the virus if they have vitamin deficiency or other health problems/issues.
