Background: Influenza mortality has dramatically decreased in France since the 1950s. Annual death rates peaked during two pandemics: the Asian flu (1956–1957) and the Hong Kong flu (1969–1970).

Objective: This study’s objective is to evaluate whether the second pandemic created a structural change in the dynamics of influenza mortality in France.

Methods: We employ a new database on influenza mortality since 1950 at the subnational level (90 geographic areas) to estimate statistical models to find out whether a structural change happened and to explain the differences in mortality rates across geographic areas. Influenza mortality increased between 1950 and 1969 and decreased from 1970 onward.

Conclusions: The Hong Kong flu is identified as the event of a structural break. After the break, geographical differences are less explained by regional characteristics such as income, density, or aging ratio. The Hong Kong flu was found to be associated with a major change in influenza mortality in France. Change in health practices and policies induced a decline in mortality that started in 1970, just after the pandemic. The health benefits are notably important for senior citizens and for the poorest regions.

Contribution: We employ a new database on influenza mortality since 1950 at the subnational level (90 geographic areas). Change in health practices and policies induced a decline in mortality that started in 1970, just after the pandemics. The health benefits are notably important for senior citizens and for the poorest regions.