LIEPP Working Paper October 2020, nº112 The medium-term impact of non-pharmaceutical interventions. The case of the 1918 Influenza in U.S. cities Guillaume CHAPELLE CY Cergy Paris-Université, LIEPP
[email protected] www.sciencespo.fr/liepp © 2020 by the authors. All rights reserved. How to cite this publication: CHAPELLE, Guillaume, The medium-term impact of non-pharmaceutical interventions. The case of Influenza in U.S. cities, Sciences Po LIEPP Working Paper n°112, 2020-10-22. The medium-term impact of non-pharmaceutical interventions. The case of the 1918 Influenza in U.S. cities ∗ Guillaume Chapelle † First version April 11, 2020; this version October, 2020 Abstract This paper uses a difference-in-differences (DID) framework to estimate the impact of Non-Pharmaceutical Interventions (NPIs) used to fight the 1918 influenza pandemic and control the resultant mortality in 43 U.S. cities. The results suggest that NPIs such as school closures and social distancing, as implemented in 1918, and when applied for a relatively long and sustained time, might have reduced individual and herd immunity and the population general health condition, thereby leading to a significantly higher number of deaths in subsequent years. J.E.L. Codes: I18, H51, H84 Keywords: Non-pharmaceutical interventions, 1918 influenza, difference-in-differences, health policies ∗The author acknowledges support from ANR-11-LABX-0091 (LIEPP), ANR-11-IDEX-0005- 02 and ANR-17-CE41-0008 (ECHOPPE). I thank Pierre Andr´e,Richard Baldwin, Sara Biancini, Sarah Cohen, Sergio Correa, Ma¨elysde la Rupelle, Rebecca Diamond, Jean Beno^ıtEym´eoud, Maud Giacopelli, Laurent Gobillon, Pierrick Gouel, Laurence Jacquet, Andrew Liley, Matthew Liley, Philippe Martin, Gianlucca Rinaldi, Alain Trannoy, Etienne Wasmer, Clara Wolf, Charles Wyplosz and participants to the THEMA Lunch seminar for their helpful comments on this working paper.