The Days All Went Viral

Sickness 001: Virus Day

Without a doubt.
Death sucks.
William Zed had been walking when all of a sudden, a man that was walking on the other side of the street started gagging, then collapsed.
Apparently, he was dead.
A woman rushed up to see if the man was okay, but collapsed as well. They were both dead.
Quickly, more and more people collapsed, and even flies that started flying nearby died.
It was a deadly virus.
William looked at the area surrounding the dead people, and saw a greenish-brown mist-like substance surrounding them, as well as in the building the first man had come out of. People inside the building were also dead.
Starting to get the gist of how people were dying, others started avoiding it, but those nearby the scene carried the smoke with them.
It was a virus that had come to kill us all.
All except William, that is.

William had walked near the pile of dead bodies, but when he looked at himself, he didn't get the sickening aura. He was immune to the new virus.
There was only one explanation.
He popped out his right eye contact, the only contact he wore, and looked in a mirror.
There, staring back at him, were two different colored eyes. One was black.
The other was red.