Polio Vaccine — Jonas Salk and Albert Sabin (1955/1961)

Salk's injected inactivated virus vaccine and Sabin's oral live-attenuated version together drove polio from a terrifying global scourge to near-eradication. At its peak, polio paralyzed over 350,000 children annually; by 2025, wild poliovirus cases numbered fewer than a dozen worldwide.