"This would result in these individuals contracting a milder form of smallpox, and upon recovery, they would gain immunity to the disease. Although this technique had a 1-3% mortality rate, it was significantly lower than the 20-30% mortality rate associated with smallpox itself. This practice of deliberately exposing healthy individuals to smallpox-infected material in the hopes of providing immunity was known as variolation.

The earliest documented case of variolation involves a Buddhist nun living on a mountain named O-Mei Shan in the southern province of Szechuan, China, during the period between 1022 and 1063 AD. She began practicing variolation after noticing that those who survived smallpox did not contract the disease again. It wasn't until 1796 that English Physician Edward Jenner discovered a vaccination for smallpox. He achieved this by injecting pus from a cowpox sore found on a milkmaid into an eight-year-old boy. Six weeks later, he attempted to infect the boy with smallpox, but the boy did not develop the disease, indicating that the prior exposure to cowpox had protected him from infection."