"No, but I've heard of them." An outside virus. Yeah, that was almost worse. "Maybe something that evolved on a place similar to Earth, then? And your DNA was ready to fight it, but anyone with different DNA...wasn't."
It was the simplest explanation, and John knew that meant it was probably the most correct one. He rubbed his chin, staring at the chains of DNA in front of him and then shaking his head.
"How could you create a cure for something like this? Or a vaccine?" One that would be equipped to handle so many different types of...well, people. Species. John glanced at Tony. "Assuming that's what you're trying to do, I mean." There was the thing of a smile. He had a feeling Tony was concerned with keeping everyone healthy, maybe figuring it out. John was looking for a practical solution for a next time. Just in case.