I have found this on Underwold wiki page that is about The Purges:
The Purges are a series of mass killings against the Lycans and Vampires after humans discover their hidden existence.
In Underworld: Blood Wars, the Purges appear to have ceased. No explanation is provided for this; it’s possible that the surviving Immortals were able to escape death by hiding from the humans until the human governments concluded that the Vampires and Lycans were extinct. The humans are presumably aware that some immortals could have survived, but the Vampires and Lycans continued their war with each other while largely ignoring or avoiding humans.
I have also found this on reddit discussion about Underworld: Blood Wars:
In Awakening, lycans are still in abundance, posing as humans. They have power and even cleared over 200 suspected Lycans. So Lycans and Vampires are among humans, but there are so many and they are in positions of power that its become easier for them to grow while hiding among everyone.
Based on those two findings we can assume that the humans believe that both Vampires and Lycans are extinct, but in reality they are posing as humans and secretly still fighting each other.