Ring Vaccination for Smallpox

Ring vaccination is a strategy to control disease. It was used to control smallpox until the last naturally occurring case in 1977. When an infection was diagnosed, all people who were or may have been exposed were found and vaccinated. Then a second "ring" of people who may have been exposed to the first ring were also found and vaccinated.

Many disease-control experts support ring vaccination instead of mass vaccination of the American public.