Is it ensure, insure, or assure?
in reference to polio vaccine, 1955, from name of Russian-born U.S. microbiologist Albert B. Sabin (1906-1993).
Sabin Sa·bin (sā'bĭn), Albert Bruce. 1906-1993.
American microbiologist and physician who developed a live-virus vaccine against polio (1957), replacing the killed-virus vaccine invented by Jonas Salk.
Sabin , Florence Rena. 1871-1953.
American pioneer anatomist noted for her investigations of the lymphatic system. She was the first woman elected to the National Academy of Sciences (1925).