Idiots.
Yeah, the computers ONLY turn on the virus on April 1st. After that, the computers that dodged it... *WHEW*.
Okay, this virus is a botnet. What it does it infect computers silently, nestles in there hard drive and waits. At a set date, or when it's infected enough computers, it phones home to the virus creator. The computers that have been infected simultaneously send the virus out to other computers and log personal information. Keystrokes and such. And sends it back to the person that created it, basically.
So, this isn't a point on a graph. It's a ray.