Many years ago there were vaccines discovered that prevented these two illnesses. Children before that were very ill when they got these diseases. Many of them died. After the vaccine was discovered and children were inoculated, both diseases virtually went away. However, later on parents decided not to get these vaccines because they did not trust them and both diseases began to come back and then were spread to others one at a time in daycares. That is the way a virus gets around in a computer group also.
Not too long ago, as an example, a friend who takes care of a computer system in a hospital noticed a virus warning that kept moving around. Eventually it was everywhere. It was nearly impossible to get rid of. It got in through a computer that someone forgot to load the virus software on and that nurse had been out on the web. It was a very expensive mistake. The connection between a companys computer and home users is the same as my touching your hand and you passing me a virus. If you had flu shot and not got the virus, you would not have passed it to me.
Virus software, of course, affects network security but so does malware (infoworld.com). Many IT specialists say that these are now worse than the Trojans were and are. Malware sends in search mechanisms that get deep into the computer information and pull out personal things like all your employees security information or the companys security information. These are set up, not by hackers but by people that are out there to make a profit on your information and it only takes visiting the web at the wrong site or downloading the wrong file. This is truly dangerous to your organization and to any of your employees that may be working from their own PCs at home.
In todays world, we are all touched by computers and like keeping personal and important information that is in paper form secure, so is it