well I might be wrong but I think that that's either the only way for vampires to reproduce (with a human) or they can't at all (as there sperm is technically dead)

I thought a vampires whole body was dead that's why their bodies are cold. So wouldn't that mean he shouldn't be able to produce sperm at all

Whaaat?

Why is my comment cut off?

Why is my reply with multiple sentences not showing?

It depends on the lore. Some people tweak the vampire lore a bit and have it where vampires are just a different type of "human" - alive and able to reproduce with normal humans, but have different attributes. So we really just have to see where the author wants to go with this

True. It does depend on how the author view vampires and their genetics