When was the polio vaccine developed?

• A. Late 1950s to early 1960s
• B. 1930s
• C. 1960s to 1970s
• D. 1980s

Answer: (A)

Polio vaccines became available during the mid-20th century, with two major breakthroughs driving public use in quick succession. Salk developed an inactivated (killed) poliovirus vaccine that was announced and licensed in the mid-1950s, after large trials showed it was safe and effective. Soon after, Sabin developed a live-attenuated oral vaccine, which was licensed in 1961 and became widely used. When you look at the timeline for when vaccination programs began in earnest and vaccines entered general use, the period from the late 1950s to the early 1960s best fits. The other options place development too early or too late, since vaccines weren’t available in the 1930s, and by the 1960s–70s or 1980s vaccination was already established, not newly developed.