Oh my gosh this reminds me of that Dustin Hoffman movie. It scares me to think that modern medicine doesn't always have the answer. Through extensive medicinal use, we create strains of bacteria that are resistant to drugs. Would we be able to come up with a solution? Probably, but not before the damage is done, as seen with past pandemics.
The aftermath reminds me of both Revolution and Surrogates (tv show and movie respectively). After a major change has occurred, the structure and foundations of the world as we know it, will collapse most likely, in all different facets (assuming extinction-level). We'll survive, but things will branch off, no large societies would be able to function properly. Because essentially, wiping out half the planet is wiping out the power, the infrastructure, etc. I'm not saying we start off from scratch, but things become rather primitive to start off with, people become hysteric and fall into different groups, nothing is organized, and it'll take a long long time, probably never, before the world gets back on its feet.