[he0001]

Virus exist everywhere and is the most common entity on earth. In a tablespoon of seawater there can be ten million of them. Most are not dangerous to man, about 600 is known. They are also very good to survive on their own without a host and can live in most hostile environments.

[soldehierro]

Viruses aren't alive, and they certainly can't reproduce without host cells, so saying that they survive on their own doesn't seem like a terribly accurate statement. Trying to extend the metaphors of life "alive or dead, surviving" to viruses only generates misconceptions, instead "viable or inactivated" is a better way of looking at it.