URL: https://www.medrxiv.org/content/10.1101/2020.05.23.20111302v2
Type d’article :
Preprint
Thème : Autre : Economie, santé publique
Que retenir de cet article, en 1-2 phrases ? :
The authors investigate the consequences of wearing face masks on a potential risk increase of covid propagation, among the American population, using data collected by a device/company. They conclude that people spent more time outside their homes and more time in restaurants, potentially favoring disease propagation.
Objectifs de l’étude / Questions abordées :
The objective is to contribute to the economic and public health literature concerning COVID-19, by using the variation in face mask mandates along with mobile device data to measure the change in the amount of time Americans staying at home, and the number of visits Americans made to public places following face mask mandates.
Méthode :
The authors use SafeGraph smart device location data (according to the authors, SafeGraph is a data company that aggregates anonymized location data from numerous applications in order to provide insights about physical places). For a county i at day t, they regress time spent at home (measured as the device weighted average per county of median home dwell time by census block group, in minutes) on the first mask order. They also account for several variables in the regression: county-level weather, reported cases in one’s own county and nationwide, a county-specific fixed effect and a weekday specific fixed effect. The main assumption is that people spend less time at home once they receive a directive to wear masks.
Résultats principaux :
The authors find evidence that masks enable disinhibition behavior and that Americans spend less time at home (20-30 minutes less time at home) and more time in moderate to high-risk locations following orders to wear masks. According to the authors, “Time at home fell, and visits to public places rose” which is likely a risk compensating behavior, because face masks are of questionable effectiveness when used in the general population.
Commentaire/brève évaluation :
The manuscript is easy to read and most of the methodology is efficiently introduced. A description of data gathered by SafeGraph would have been appreciated, it is not possible to determine the exact nature of data used. No comparison of regressions and data is shown, so it is difficult to evaluate the accuracy of the conclusions. However, the question raised and the discussion associated with mandatory face mask wearing and the consequences on the disease propagation are relevant.