Department of Business and Economics, University of Southern Denmark, 5230 Odense, Denmark.
Institute of Economics, Universität Kassel, 34127 Kassel, Germany.
Proc Natl Acad Sci U S A. 2020 Dec 22;117(51):32293-32301. doi: 10.1073/pnas.2015954117. Epub 2020 Dec 3.
We use the synthetic control method to analyze the effect of face masks on the spread of COVID-19 in Germany. Our identification approach exploits regional variation in the point in time when wearing of face masks became mandatory in public transport and shops. Depending on the region we consider, we find that face masks reduced the number of newly registered severe acute respiratory syndrome coronavirus 2 infections between 15% and 75% over a period of 20 days after their mandatory introduction. Assessing the credibility of the various estimates, we conclude that face masks reduce the daily growth rate of reported infections by around 47%.
我们使用合成控制法分析了口罩对德国 COVID-19 传播的影响。我们的识别方法利用了口罩在公共交通和商店强制佩戴的时间在各地区的差异。根据我们考虑的地区不同，我们发现口罩在强制引入后的 20 天内，将新登记的严重急性呼吸系统综合症冠状病毒 2 感染数量减少了 15%至 75%。评估各种估计的可信度后，我们得出结论，口罩使报告感染的日增长率降低了约 47%。
