That is a very good question. It will be for DNA-based IDs and to be able to track post-jab genetic changes in individuals.
But it could also be used to try to identify and map gene pattern correlations in those who present specific behaviours such as obedience and disobedience, compliance and non-compliance.
Imagine the power they could have to remake the population into obedient drones using clearly defined and targeted genetic manipulation? Only eugenecists would need the blueprints to every human.
if I've thought of that as a possibility, I'm damn sure they will have too