In 1100, the variolation technique was developed, involving the inoculation of children and adults with dried scab material recovered from smallpox patients.

In Asia, practitioners developed the technique of variolation—the deliberate infection with smallpox. Dried smallpox scabs were blown into the nose of an individual who then contracted a mild form of the disease. Upon recovery, the individual was immune to smallpox. Variations of variolation have been noted in Turkey, Africa, China, and Europe.