The vaccine that keeps your kids from getting polio wasn’t invented by Jonas Salk.
It was invented by Albert Sabin, who developed a vaccine that was stronger, cheaper to make, easier to take, and less likely to cause polio infection than Salk’s original. Sabin’s vaccine was licensed in 1962, and remains the standard today.
Even incremental changes can be patentable—and are often highly valuable to the patent holder.