Digital Global Public Health, Hasso Plattner Institute, University of Potsdam, Potsdam, Germany.
Institute for Medical Informatics, Charité - Universitätsmedizin, Berlin, Germany.
JMIR Public Health Surveill. 2024 Mar 8;10:e49307. doi: 10.2196/49307.
The question of the utility of face masks in preventing acute respiratory infections has received renewed attention during the COVID-19 pandemic. However, given the inconclusive evidence from existing randomized controlled trials, evidence based on real-world data with high external validity is missing.
To add real-world evidence, this study aims to examine whether mask mandates in 51 countries and mask recommendations in 10 countries increased self-reported face mask use and reduced SARS-CoV-2 reproduction numbers and COVID-19 case growth rates.
We applied an event study approach to data pooled from four sources: (1) country-level information on self-reported mask use was obtained from the COVID-19 Trends and Impact Survey, (2) data from the Oxford COVID-19 Government Response Tracker provided information on face mask mandates and recommendations and any other nonpharmacological interventions implemented, (3) mobility indicators from Google's Community Mobility Reports were also included, and (4) SARS-CoV-2 reproduction numbers and COVID-19 case growth rates were retrieved from the Our World in Data-COVID-19 data set.
Mandates increased mask use by 8.81 percentage points (P=.006) on average, and SARS-CoV-2 reproduction numbers declined on average by -0.31 units (P=.008). Although no significant average effect of mask mandates was observed for growth rates of COVID-19 cases (-0.98 percentage points; P=.56), the results indicate incremental effects on days 26 (-1.76 percentage points; P=.04), 27 (-1.89 percentage points; P=.05), 29 (-1.78 percentage points; P=.04), and 30 (-2.14 percentage points; P=.02) after mandate implementation. For self-reported face mask use and reproduction numbers, incremental effects are seen 6 and 13 days after mandate implementation. Both incremental effects persist for >30 days. Furthermore, mask recommendations increased self-reported mask use on average (5.84 percentage points; P<.001). However, there were no effects of recommendations on SARS-CoV-2 reproduction numbers or COVID-19 case growth rates (-0.06 units; P=.70 and -2.45 percentage points; P=.59). Single incremental effects on self-reported mask use were observed on days 11 (3.96 percentage points; P=.04), 13 (3.77 percentage points; P=.04) and 25 to 27 (4.20 percentage points; P=.048 and 5.91 percentage points; P=.01) after recommendation. Recommendations also affected reproduction numbers on days 0 (-0.07 units; P=.03) and 1 (-0.07 units; P=.03) and between days 21 (-0.09 units; P=.04) and 28 (-0.11 units; P=.05) and case growth rates between days 1 and 4 (-1.60 percentage points; P=.03 and -2.19 percentage points; P=.03) and on day 23 (-2.83 percentage points; P=.05) after publication.
Contrary to recommendations, mask mandates can be used as an effective measure to reduce SARS-CoV-2 reproduction numbers. However, mandates alone are not sufficient to reduce growth rates of COVID-19 cases. Our study adds external validity to the existing randomized controlled trials on the effectiveness of face masks to reduce the spread of SARS-CoV-2.
在 COVID-19 大流行期间，口罩在预防急性呼吸道感染方面的效用问题再次受到关注。然而，鉴于现有随机对照试验的证据并不确定，因此缺少基于具有高度外部有效性的真实世界数据的证据。
为了增加真实世界的证据，本研究旨在检验 51 个国家实施口罩强制令和 10 个国家提出口罩使用建议是否增加了自我报告的口罩使用量，并降低了 SARS-CoV-2 繁殖数和 COVID-19 病例增长率。
我们应用事件研究方法，对来自四个来源的数据进行了汇总分析：（1）从 COVID-19 趋势和影响调查中获取了关于自我报告口罩使用情况的国家层面信息；（2）牛津 COVID-19 政府应对追踪器的数据提供了有关口罩强制令和建议以及实施的任何其他非药物干预措施的信息；（3）谷歌社区流动性报告中的流动性指标也被纳入研究；（4）从 Our World in Data-COVID-19 数据集获取了 SARS-CoV-2 繁殖数和 COVID-19 病例增长率。
平均而言，强制令使口罩使用率增加了 8.81 个百分点（P=.006），SARS-CoV-2 繁殖数平均下降了 0.31 个单位（P=.008）。虽然强制令对 COVID-19 病例增长率没有显著的平均影响（减少 0.98 个百分点；P=.56），但结果表明在实施强制令后的第 26 天（减少 1.76 个百分点；P=.04）、第 27 天（减少 1.89 个百分点；P=.05）、第 29 天（减少 1.78 个百分点；P=.04）和第 30 天（减少 2.14 个百分点；P=.02）存在增量效应。对于自我报告的口罩使用和繁殖数，在强制令实施 6 天和 13 天后观察到了增量效应。两种增量效应都持续超过 30 天。此外，口罩使用建议平均使自我报告的口罩使用量增加了 5.84 个百分点（P<.001）。然而，建议对 SARS-CoV-2 繁殖数或 COVID-19 病例增长率没有影响（减少 0.06 个单位；P=.70 和减少 2.45 个百分点；P=.59）。在建议发布后的第 11 天（增加 3.96 个百分点；P=.04）、第 13 天（增加 3.77 个百分点；P=.04）和第 25 天至 27 天（增加 4.20 个百分点；P=.048 和增加 5.91 个百分点；P=.01）观察到了自我报告的口罩使用的单增量效应。建议还影响了繁殖数在第 0 天（减少 0.07 个单位；P=.03）和第 1 天（减少 0.07 个单位；P=.03）以及在第 21 天至 28 天（减少 0.09 个单位；P=.04）和第 28 天至 28 天（减少 0.11 个单位；P=.05）之间以及在病例增长率在第 1 天至第 4 天（减少 1.60 个百分点；P=.03 和减少 2.19 个百分点；P=.03）和第 23 天（减少 2.83 个百分点；P=.05）之间的变化。
与建议相反，口罩强制令可以作为减少 SARS-CoV-2 繁殖数的有效措施。然而，仅强制令不足以降低 COVID-19 病例增长率。我们的研究为口罩在减少 SARS-CoV-2 传播方面的有效性的现有随机对照试验增加了外部有效性。
