Triggered effects

Hi

Last night I used Vampiric Disease on a locked vampire with 1 blood left. It had a Vessel. Qustions arised about if was possible to order effects so you could take the blood prior to unlock. I said that it being triggered by unlocking, which is the first thing that happens on unlock phase. We all sort of agreed on that it made sense but it left me wondering: Is that difference between activated effects and triggered effects defined in VTES? I know them from Magic but I'm not sure if them apply here and if so, what's their timming? I know we use mandatory actions in that direction but I could'n find another instance.

Many thanks in advance

Vampiric Disease

Master.
Put a disease counter on any vampire. Each time a vampire with a disease counter is in combat at close range with another vampire, the second vampire gets a counter as well. An afflicted vampire cannot gain blood by hunting. When an afflicted vampire untaps, he or she burns a blood or, if unable, burns the disease counter. A vampire can have only one disease counter.