Déchiffrer la grippe russe. Quand une pandémie devient un événement statistique (1889-1893)

The use of figures to describe the magnitude and extent of a flu epidemic constituted a scientific innovation in late 19th-century France. The article describes the role of French statisticians, such as Jacques Bertillon and Victor Turquan, in revising and revealing figures attesting to the gravity of the 1889?1890 flu episode, a feat achieved by calculating excess mortality over the period. The statistical studies done in France between 1890 and 1893 not only found an unprecedented level of mortality for the country?one that stood out at the scale of the century?but also contributed a decisive argument for the hypothesis that the flu spread through contagion. They also served to confirm the information presented by the new press of the time, which, thanks to the telegraph, had been able to follow the spread of the epidemic sooner than other institutions. But at the political level, and in light of the preoccupying trend of ?depopulation? in 19th-century France, the new studies? results were also used to relegate the flu as an ?accidental cause? in the worrying national population situation. Because the new statistics captured the flu indissociably from the complications and lethality it causes, the excess mortality continues to be used to this day to measure the impact of flu episodes.