How do ring vaccination campaigns stop outbreaks like smallpox?

Ring vaccination identifies an infected person and then vaccinates their close contacts, and often the contacts of those contacts, creating a protective buffer. This strategy works best for diseases that spread through identifiable contacts and where cases can be found and isolated quickly. It was crucial in the final global campaign to eradicate smallpox, led by the World Health Organization in the 1970s. The approach has also been used during outbreaks such as Ebola in some settings. Ring vaccination is a targeted public health tool rather than a blanket population-wide campaign.