What the fuck are you talking about? It took years to get under control. The entire book is set twenty years after the outbreak began, and there’s still tens of millions of zombies around, just pushed back out of inhabited areas and kept away as they slowly decompose. Pakistan and Iran nuked each other into oblivion. The entire global society basically broke down when it was released that Phalanx (the vaccine being hawked) was a scam. Billions of people died.

It was four years after the outbreak started that the US built up to go on the offensive, another three years before they liberated the contiguous US, and another two years after that that it was declared victory globally. Seven years after the outbreak began.