Koprowski died of pneumonia April 11 at his Philadelphia home, said his son, Dr. Christopher Koprowski, a radiation oncologist.
In 1950, Hilary Koprowski showed that it was possible to use his live-virus oral vaccine against polio, which had plagued the United States and other countries for decades.
Another researcher, Dr. Albert Sabin, would win the race to get an oral vaccine licensed in the U.S. while Jonas Salk would develop an injectable vaccine that eliminated much of the disease in the country.
The two other scientists were far better known for helping to eradicate polio, but Koprowski's contribution was considered groundbreaking.
"Both Salk and Sabin became public figures, quite justifiably," Koprowski told the Philadelphia Inquirer in 2000. "They traveled the world, meeting presidents and kings, whereas I got to continue my work. I believe this was a better way for me."
Controversy often followed the feisty Koprowski.
He spent years defending his polio research after writer Edward Hooper argued in his 1991 book "The River" that Koprowski's vaccine trials in the Congo may have inadvertently triggered the AIDS pandemic. Scientific experts conclusively debunked the theory in 2001.
From 1957 to 1991, Koprowski served as director of Philadelphia's Wistar Institute and was credited with transforming it into a renowned biomedical research facility. Under his leadership, scientists developed a German measles vaccine and a more effective vaccine for people exposed to rabies, according to Wistar.
With fellow scientists, Koprowski also developed a technique in the 1970s to produce monoclonal antibodies, which are now used to fight cancer.
After Wistar fired Koprowski in 1991 amid financial problems, he filed age-discrimination claims. One issue was the money he made from Centocor, a biotechnology company he co-founded while at Wistar, the Inquirer reported in 2000.
He then became director of Biotechnology Foundation Laboratories Inc. at Thomas Jefferson University in Philadelphia. While there he worked on genetically engineering plants to produce vaccines.
But when his grant funding declined and Jefferson reduced his office space, he cited age discrimination issues and ended up in court in 2010. He ultimately dropped any legal action and retired in 2011.
"He was colorful, charismatic," his son said, and "the most brilliant person I've ever met."
An only child, Koprowski was born in 1916 in Warsaw, Poland. By age 5 he spoke several languages and played piano.
At 12, he entered the Warsaw Conservatory of Music, but the ability of another gifted piano player made Koprowski think he would never be good enough to make it as a concert pianist, he later said.
While studying medicine at the University of Warsaw, he met his future wife, Irena. They had been married for 74 years when she died last year.
When the Germans invaded Poland, the couple fled to Brazil in 1939. Penniless, he gave piano lessons before he began working in a lab.
After moving to the U.S. in 1944, he soon "took on polio," he later said, "because it was a big, important disease."
Survivors include his two sons, Christopher and Claude.