Change Vampire to something unique

[DyssalC]

That could work.

A vampire could just carry a syringe of vampire blood and if they want to save their victim they can inject.

Perhaps chance of infection could be tied to health. critical health is a higher chance of infection, 100% health is a low/0 chance of infection.

A vampire would have to resuscitate it's victim in order to have a vampire servant or hope that the odds are in their favor, so infection would take longer.

fighting off the infection could also convert vampire blood into an antidote.

Inject someone or a monkey with vampire blood at full health and if they don't turn extract the blood and now you have antibodies for pathology to look at. Otherwise you have a brain dead vampire monkey.

This almost sounds like vampire spy mode.
But that isn't a bad thing.