The Great Anti-Virus Development Race
As far as being up to date in the world of viruses and issues on the web, most anti-virus software companies today are trying to aggressively find ways to make their respective software recognize these harmful files that plague the web.
Based on statistics from past years, the rampant growth of viruses and malware have been a cause for concern and most anti-virus software available today have their own line of preference in identifying and curing such problems. If you look at it, there is no single software that can safely protect your computer. They just have to work together and produce that one complete anti-virus software everyone can count on.
(Source) The Washington Post