According to the Monster Manual entry for vampires, the Bite attack has the following effects, once successful:
Hit: 7 (1d6 + 4) piercing damage plus 10 (3d6) necrotic damage. The target's hit point maximum is reduced by an amount equal to the necrotic damage taken, and the vampire regains hit points equal to that amount. The reduction lasts until the target finishes a long rest. The target dies if this effect reduces its hit point maximum to 0. A humanoid slain in this way and then buried in the ground rises the following night as a vampire spawn under the vampire's control.
If the player character doesn't die and is able to retreat (or defeat the vampire) and take a long rest, are there any long-term or permanent consequences of this bite? Besides the mental trauma, of course?