the virus is active when they are inside living things (host cell)
They are active only when they are inside a living 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.
They are not active and do not make new viruses.
Remaining healthy is important if a person wishes to live longer, or be active for longer periods of time. Viruses are very tricky to treat, because they live within blood cells, there are only few antiviral medications around.
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
Lipophilic viruses require the lipid (fatty) envelope to remain active ("live"*), and the fatty layer can be destroyed by alcohol. Non-lipophilic viruses do not require this fatty envelope, and the protein layer (capsid) is more resistant to alcohol. *Note: viruses are not actually alive, they are only genetic codes with 1 or 2 (lipophilic) protective layers. Biologists call "live" viruses *active* and "dead" viruses *inactive* or *inactivated*.
There are no active viruses that affect Mac OS X.
When it is inside a living 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.
unitedairlines.com is as safe as any other reputable travel website. The airlines says their site is very secure and at current time do not have any active viruses related to their site.