While I can't remember for sure, I'd assume the first wave of VITAS wasn't cured just by, you know, a cure. It killed off a sizable fraction of the world's human population in a very short amount of time, while leaving the people who were resistant. Basically, it probably would have killed itself off by slaughtering viable hosts faster than it could infect them. This is one of the biggest issues with biological warfare, actually; you have to balance mortality, contagiousness and a number of other factors (incubation time, symptoms, etc.).
They probably survived by implementing martial law and other methods of control while the chaos was all around them, and then put the pieces back together after. As the reconstruction efforts moved on, I bet the megacorporations and their predecessors were snapping up every opportunity to get money and concessions out of the world's governments. Keep in mind, a lot of nations still fell apart later on, and I would bet my britches that VITAS was a factor, even decades after. Would the NAN have been so successful if such a disaster hadn't weakened the States? Would Japan have had the motivation to go back to their Imperialistic roots without such a disaster bringing a need for the past back? A lot of factors come to mind.
I wouldn't say VITAS is played down all that much, at least in comparison to other epidemics and pandemics that took place in the past. I mean, folks barely remember typhoid epidemics, the Spanish Flu, polio, smallpox and even the Black Death is generally a paragraph or two unless you're researching more thoroughly. People tend to forget that kind of thing, excepting the ones who lived through it.
