In the 16th century, the Turks were already using a method to innoculate themselves against small-pox.
Before their babies turned 6 months old, they made a small incision in its arm and carefully introduced small-pox germs that were taken from the body of another child. This artificial introduction of the pathogen imbued the child with immunity against the disease.
This practice was in place long before Edward Jenner discovered vaccination.
We tend to think of scientific research leading to cutting-edge technology. But more often than not, the arrow moves in the opposite direction.
We made boats before we understood bouyancy. Glassmaking was invented 4000 years ago, well before we understood its science. Gunpowder was invented way before the Chemistry we now use to explain it. James Watt and Thomas Newcomen invented the steam engine before the advent of Thermodynamics and the Carnot cycle.
Innovation stems more from use than from understanding. To innovate, you are better off tinkering around to see what works, rather than cultivating the perfect theory to later put it into practice.
Inpsiration: How innovation works