The variolisation is the voluntary inoculation of the Variole, taken on a subject slightly sick, or itself variolized. This technique, which goes back to the old China, protects the subjects from a serious variola. Its unreliability (nothing proves that the variolized subject will not make a variola engraves), the risk of dissemination of variola led to its abandonment after the discovery of the Vaccination

This practice consisted in inoculating a form which one hoped for not very virulent variola by putting in contact the person to be immunized with the suppurant contents of the substance of the blisters of a patient. The result remained however random and risky, death rate could reach 1 or 2  %. In 1760, Daniel Bernoulli showed that, in spite of the risks, the generalization of this practice would make it possible to gain a little more than three years of life expectancy to the birth.

As of the 11th century, the Chinese practiced the variolisation. It is the Prime Minister Wang daN who after the loss of one of his sons of variola had convened various experts of all the China to develop a disease prevention. A monk taoist brought the technique of inoculation which was diffused gradually in all China. The practice was gradually propagated along the Silk route. In 1701, Giacomo Pylarini carries out the first inoculation with Constantinople. The technique is imported in Occident at the beginning of the 18th century, by Lady Mary Wortley Montagu the woman of the ambassador of England in Turkey.

It is introduced in France by the doctor Theodore Tronchin in 1756. The practice is initially disputed, but a certain number of large characters give the example: the duke of Orleans makes vaccinate his/her son, the duke of Chartres, which does itself to vaccinate its sons, the duke of Valois and the duke of Montpensier, on April 6th 1779.