If people start falling like flies because of the vaccine, it's not going to fly very long before a serious resistance is met, which would be counter productive in the end. There's a need to leave rooms for doubt, so people fail to easily connect the dots, so by the time they eventually do, it's too late However, if it puts people on a sterilization slope, gradually going impotent/infertile over a couple of years after taking the vaccine, that's nice, from a population reduction stand point. Of course a cancer bonus is always a plus