What Did Dr. Jenner Tell Rick On "The Walking Dead"?

From the Washington Post article:

Lincoln, who says the comments are “pivotal” for Rick, hints that the message was not good news. 

“This is a scientist who seemingly held all the cards to what this epidemic is about and I do think, you know, you would imagine he would have something of value to say on that matter,” Lincoln said. “Well, he chose to kill himself.”