If the WHO kills everyone who takes the vaccine they will:
A) Look stupid and unable to successfully govern
B) Show they're true face
C) Lose the faith of the public
D) Failed to prevent a crisis
Any of those are dangerous to they're agenda.
This is an anti-fertility vaccine.
They want to build the public's trust and confidence.
An anti-fertility vaccine will be almost impossible to prove, as most of the children they are targeting will not even be thinking about procreating for another 15 years, plenty of time to forget about the shot.