Players on the infected team are only armed with a knife, but they have increased mobility to make up for it.
If a survivor is killed, they switch teams. Like most incarnations of the game mode, Infected in Modern Warfare pits a team of survivors against a relentless onslaught of infected players. Since its original appearance, it has gone on to appear in several other Call of Duty titles.
It originally began as a private match game mode before becoming a fully-fledged public game mode in 2012. Infected is a game mode that its debut in Call of Duty: Modern Warfare 3. Other Season 1 content, like the new maps, Vacant and Shipment, and the new Operator, Nikto, have yet to make an appearance in Modern Warfare but are scheduled to be released before the season comes to a close. The game mode will be coming to public playlists in the future, although it isn’t exactly clear when. From there, you can invite some friends and start the game.
Switch to the Alternate Modes tab and Infected should be on the list. To create a lobby, go to the Multiplayer menu in Modern Warfare.