Although now at the forefront of molecular technologies, vaccination has a history in the West going back at least 200 years (vacca - «cow» refers to Edward Jenner's use of cowpox against smallpox). (euvaccine.eu)
If you work on vaccines you know the story of British physician Edward Jenner, whose observation that dairymaids infected with cowpox made them resistant to the far more virulent smallpox virus led him to develop, in 1796, the first experimental vaccine. (iavireport.org)
Pexa - Vec is an engineered virus based on the harmless vaccinia cowpox virus — also the basis for the original smallpox vaccine. (ucsf.edu)