Although, just because they didn't get everyone, doesn't necessarily mean they have given up. They are working on self-replicating mRNA, as well as injecting all their new vaccines into the food supply. Who knows what they'll try next.
I remind myself the last time they were in a position to really shake up the system was just after the second world war. If it worked in the past, and their other thing didn't work as expected, why not try a global conflict again in some capacity?