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WP/21/205
IMF Working Paper
Western Hemisphere Department and Research Department
Mask Mandates Save Lives
Prepared by Niels-Jakob H. Hansen and Rui C. Mano1
Authorized for distribution by Nigel Chalk
August 2021
IMF Working Papers describe research in progress by the author(s) and are published to elicit comments and to encourage debate. The views expressed in IMF Working Papers are those of the author(s) and do not necessarily represent the views of the IMF, its Executive Board, or IMF management.
Abstract
We quantify the effect of mask mandates in the United States in 2020. Our regression discontinuity design exploits county-level variation in COVID-19 cases, hospital admissions, and deaths across the border between states with and without mandates. We find a significant and substantial effect—mask mandates reduced new weekly COVID-19 cases, hospital admissions, and deaths by 55, 11 and 0.7 per 100,000 inhabitants on average. Crucially, we find that the effect of mask mandates depends on the attitudes toward mask wearing at the county level, with larger effects in counties more positively inclined towards mask wearing. Our results imply that mandates saved 87,000 lives through December 19, 2020, while a nationwide mandate could have saved 58,000 additional lives. These large effects suggest that mask mandates are a crucial tool to counter pandemics, particularly if accepted widely by the population. Our results are thus also relevant for countries who will not be able to immunize large swaths of their population in the short term.
JEL Classification Numbers: I18, I12.
Keywords: COVID-19, public health measures, face masks, regression discontinuity.
Author’s E-Mail Address: nhansen@imf.org; rmano@imf.org
The paper has benefited from very helpful discussions with John Bluedorn, Oya Celasun, Francesco Grigoli, Deniz Igan, Hans Henrik Sievertsen, and Yunhui Zhao. We are also grateful for useful suggestions from Ruchir Agarwal, Philip Barrett, Michael Boerman, Francesca Caselli, Nigel Chalk, Paul Elger, Marta Giagheddu, Gita Gopinath, Divya Kirti, Petya Koeva, Koshy Mathai, Paolo Mauro, Mico Mrkaic, Christoph Rosenberg, Ippei Shibata, Antonio Spilimbergo, Rui Xu, and seminar participants at the IMF.