Which scientists developed the inactivated and attenuated polio vaccines that came into commercial use in 1955 and 1961, respectively?

• A. Jonas Salk and Albert Sabin
• B. Edward Jenner and Louis Pasteur
• C. Louis Pasteur and Robert Koch
• D. Alexander Fleming and Joseph Lister

Answer: (A)

Understanding who developed the polio vaccines and how they work helps identify the right match. The injected inactivated polio vaccine (IPV) was created by Jonas Salk and first licensed for public use in 1955. It uses killed virus to provoke immunity, which makes it very safe but often requires several doses to maintain protection. The oral attenuated polio vaccine (OPV) came from Albert Sabin and became available in 1961; it uses a live but weakened form of the virus, which tends to produce strong intestinal immunity and is easier to administer to large populations. The other scientists listed are known for work on vaccines or microbiology in other contexts, not for polio vaccines tied to these dates.