Final answer:
Polio was nearly eradicated due to the mass production and use of a vaccine developed by Jonas Salk. Smallpox was eradicated globally through vaccination efforts led by the World Health Organization.
Step-by-step explanation:
The disease that was nearly eradicated when society decided to mass-produce and use a vaccine created by Jonas Salk is Polio. Jonas Salk developed a successful polio vaccine using killed virus that was tested on the HeLa cell line. Mass immunization campaigns in the U.S. during the 1950s and 1960s greatly reduced the incidence of polio.
Smallpox was also a devastating disease that had a significant impact globally until it was eradicated through worldwide vaccination efforts. Led by the World Health Organization, the last diagnosed case was in 1977, and smallpox remains the only human infectious disease to have been completely eradicated from nature.