In separate American laboratories, two men working separately -- Dr. Jonas Salk and Dr. Albert Sabin -- were determined to defeat the polio virus, to end the heartbreak.
Salk's vaccine, developed in the 1950s, involved injecting a virus that was "killed, " while Sabin's vaccine -- which he worked on in the 1960s and which was administered orally -- contained a weakened version of polio.
