Objective To evaluate the personal protective effects of wearing versus not wearing surgical face masks in public spaces on self-reported respiratory symptoms over a 14 day period. Design Pragmatic randomised superiority trial. Setting Norway. Participants 4647 adults aged ≥18 years: 2371 were assigned to the intervention arm and 2276 to the control arm. Interventions Participants in the intervention arm were assigned to wear a surgical face mask in public spaces (eg, shopping centres, streets, public transport) over a 14 day period (mask wearing at home or work was not mentioned). Participants in the control arm were assigned to not wear a surgical face mask in public places. Main outcome measures The primary outcome was self-reported respiratory symptoms consistent with a respiratory infection. Secondary outcomes included self-reported and registered covid-19 infection. Results Between 10 February 2023 and 27 April 2023, 4647 participants were randomised of whom 4575 (2788 women (60.9%); mean age 51.0 (standard deviation 15.0) years) were included in the intention-to-treat analysis: 2313 (50.6%) in the intervention arm and 2262 (49.4%) in the control arm. 163 events (8.9%) of self-reported symptoms consistent with respiratory infection were reported in the intervention arm and 239 (12.2%) in the control arm. The marginal odds ratio was 0.71 (95% confidence interval (CI) 0.58 to 0.87; P=0.001) favouring the face mask intervention. The absolute risk difference was −3.2% (95% CI −5.2% to −1.3%; P<0.001). No statistically significant effect was found on self- reported (marginal odds ratio 1.07, 95% CI 0.58 to 1.98; P=0.82) or registered covid-19 infection (effect estimate and 95% CI not estimable owing to lack of events in the intervention arm). Conclusion Wearing a surgical face mask in public spaces over 14 days reduces the risk of self-reported symptoms consistent with a respiratory infection, compared with not wearing a surgical face mask. Trial registration ClinicalTrials.gov [NCT05690516][1]. The final anonymised trial dataset and statistical codes will be freely available to the public through GitHub (). [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT05690516&atom=%2Fbmj%2F386%2Fbmj-2023-078918.atom

中文翻译：

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在公共场所佩戴外科口罩对成人自我报告呼吸道症状的个人保护作用：实用随机优势试验


目的 评估 14 天内在公共场所佩戴与不佩戴外科口罩对自我报告的呼吸道症状的个人防护效果。设计实用随机优势试验。设置挪威。参与者 4647 名年龄≥18 岁的成年人：2371 名被分配到干预组，2276 名被分配到对照组。干预措施 干预组的参与者被要求在 14 天的时间内在公共场所（例如购物中心、街道、公共交通工具）佩戴外科口罩（未提及在家里或工作场所佩戴口罩）。对照组的参与者被分配在公共场所不戴外科口罩。主要结局指标 主要结局是自我报告的符合呼吸道感染的呼吸道症状。次要结局包括自我报告和登记的 covid-19 感染。结果 2023年2月10日至2023年4月27日期间，4647名参与者被随机分组​​，其中4575名（2788名女性（60.9%）；平均年龄51.0（标准差15.0）岁）被纳入意向治疗分析：2313名（50.6%） ）在干预组中，2262（49.4％）在对照组中。干预组报告了 163 起 (8.9%) 与呼吸道感染相符的自我报告症状事件，对照组报告了 239 起 (12.2%) 事件。边际优势比为 0.71（95% 置信区间 (CI) 0.58 至 0.87；P=0.001），有利于面罩干预。绝对风险差异为-3.2%（95% CI -5.2%至-1.3%；P<0.001）。对于自我报告（边际比值比 1.07，95% CI 0.58 至 1.98；P=0.82）或登记的 covid-19 感染，没有发现统计显着效应（由于干预中缺乏事件，效应估计和 95% CI 无法估计）手臂）。 结论 与不戴外科口罩相比，在公共场所佩戴外科口罩超过 14 天可以降低出现与呼吸道感染相符的自我报告症状的风险。试验注册 ClinicalTrials.gov [NCT05690516][1]。最终的匿名试验数据集和统计代码将通过GitHub（）免费向公众开放。 [1]：/lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT05690516&atom=%2Fbmj%2F386%2Fbmj-2023-078918。原子