There are going to be a lot more betas.
H7D3 was already designed to spread quickly from "bombs" disguised as deodorizers, spread like the flu before becoming strictly fluid-transferred, make the victims hyper-aggressive to spread the disease, and even keep the resulting zombies alive as long as possible by making them strip naked so they don't die of impacted crap. If you can do all of that, you can give the disease an expiration date; the initial wave of betas is just the left edge of a bell curve — eventually every surviving zombie will become a docile idiot, capable only of unskilled labor and/or breeding. The question is how the survivors will handle whoever turned the thing loose in the first place after years of fighting nothing save ferals who don't shoot back or duck. The people who created H7D3 are dead.
Because you can create a vaccine for the zombie virus, but a zombie bite will still tear a big chunk of your flesh out. There are all kinds of ways the Zombie Apocalypse can kill you that don't involve turning into a zombie yourself. The perpetrators might even have turned on each other in their bunker, like the Russian leadership at the end of the first book. For extra schadenfreude, imagine the guy distributing the spiked deodorizers getting in a completely mundane car accident and being laid up in a hospital with a broken leg and nobody to pick him up when the zombies came calling.