When it is inside a living cell.
They are not active and do not make new viruses.
Active (non-killed) viruses are living organisms.
when a virus enters a cell and is active, it cause the host cell to make new viruses, which destroy the host cell.
Active viruses are causing a disease at this time. Some can become dormant for a time and can be reactivated. Examples are cold sores and shingles.
Active Viruses
There are no active viruses that affect Mac OS X.
They are active only when they are inside a living host cell.
There are no active viruses that attack Mac OS X.
The common cold is a great example of an active virus. Also, the flu and the herpes virus are also considered to be active viruses.
Disinfection is the partial eliminatio of active growth stage bacteria and the inactibation of some viruses
the virus is active when they are inside living things (host cell)
A hidden virus is known in the words in its name "HIDDEN virus". It hides and stays inactive. The active virus is also known in its name too "ACTIVE virus". The two viruses have different ways on spreading it own kind throughout the host or hosts.