Gym associated vaccinia infection

Last week Eli blogged about a study where investigators tried to find MRSA in a gym and couldn't. Now there's a new paper in Emerging Infectious Diseases detailing a vaccinia outbreak (4 cases) associated with a gym  in Maryland. The source of the outbreak was never determined but some members of the gym were in the military. Fortunately, none of the infected had severe complications. But it begs the question: why should anyone be vaccinated with a live virus for a disease that has been eradicated?