Emergency Room

From Halopedia, the Halo wiki

Emergency Room

Emergency Room is an achievement in Halo: Reach multiplayer matchmaking added with the Anniversary Map Pack. It was unlocked by infecting three players in a single round during a matchmade Infection game.[1] The achievement could only be unlocked on an Anniversary map.

Following the shutdown of Xbox 360 Halo online services on January 13, 2022, this achievement is no longer attainable.[2][3]