In the Chantry, Strauss will give this quest if the Fledgling is working with the Camarilla. This quest can be done concurrently with More Fun With Pestilence if the Fledgling is working with both the Anarch and Camarilla factions at this point, and agrees to work with both on the problem.
Go to the Building with the same symbol as the flyer found in the final plague-carrier's residence.
Speak to him. There is no option to side with him, though you can try to do so.
Defeat Vick and his infected minions.( 1 EXP)
Return to the lobby of the cult and report back to Strauss.( 1 EXP) Strauss may also offer a cash reward or the Bloodstar talisman, depending on player choice.
It is possible to kill Bishop Vick with relative ease by first dealing with his minions, while avoiding his wild gunfire. Once they are dealt with, run to the overturned table in the southwest corner of the room and crouch behind it. Vick will run around the table but will not attack from behind and is unable to effectively flank and damage the player, who can then pop up from cover at their leisure and defeat him with little personal damage. A shotgun is a good choice for this in terms of pure damage, though as Vick moves relatively little in this situation any handgun or ranged ability should make for a quick and easy boss fight.
(True as of Unofficial Patch 9.5 - never attempted on earlier versions) The zombified minions in the boss room can be fed upon, but their blood is diseased, forcing the player character to vomit and lose some of the blood points earned by feeding. However, no health is lost when vomiting, so taking cover from Vick and taking the chance to feed can be a viable option when low on HP.
Update: Upon receiving quest (if Damsel was spoken to first):
You are looking into the cause of the epidemic for the Camarilla as well as the anarchs.
Update: Upon receiving the quest (If Strauss is spoken to first):
The regent has asked you to find the cause of the LA epidemic and put an end to it. He has suggested you speak to the anarchs at the Last Round to get more information
You have killed Bishop Vick, the head of the plaguebearer doomsday cult, thus ending their disease spreading religion. Report back to Damsel.
Update: Upon completion:
You have eradicated the plaguebearers from Los Angeles.