http://www.pcgamer.com/rainbow-six-siege-year-three-will-feature-a-co-op-event-called-outbreak/

Rainbow Six Siege year three will kick off a little differently than the previous two. Season One, called Operation Chimera, will add a pair of new operators to the action, one from France and one from Russia, but instead of a new map it will feature the launch of the game's first-ever co-op event, Outbreak, a three-player "new fantasy" about quarantine and biohazard.

Appropriately, both of the new operators will be "biohazard specialists," although it's a good bet that they're the sort of experts in the field who carry guns instead of clipboards and advanced degrees from Johns Hopkins (although I suppose it's possible they have those too). That suggests a zombie apocalypse scenario of some sort—more Killing Floor than George Romero, probably, but with the same sort of outcome.