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. 2024 Jul 24:386:e078918.
doi: 10.1136/bmj-2023-078918.

Personal protective effect of wearing surgical face masks in public spaces on self-reported respiratory symptoms in adults: pragmatic randomised superiority trial

Runar Barstad Solberg  1 , Atle Fretheim  2   3 , Ingeborg Hess Elgersma  2 , Mette Fagernes  4 , Bjørn Gunnar Iversen  4 , Lars G Hemkens  5   6   7 , Christopher James Rose  2   8 , Petter Elstrøm  2
Affiliations

Personal protective effect of wearing surgical face masks in public spaces on self-reported respiratory symptoms in adults: pragmatic randomised superiority trial

Runar Barstad Solberg et al. BMJ. .

Erratum in

Abstract

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.

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Conflict of interest statement

Competing interests: All authors have completed the ICMJE uniform disclosure at www.icmj.org/disclosure-of-interest/ and declare: support from the Centre for Epidemic Interventions Research, Norwegian Institute of Public Health; no financial relationship with any organisation that might have an interest in the submitted work in previous three years; AF has received financial support from the World Health Organization (WHO) to attend meetings it has hosted; CR is named inventor on a patent application related to vaccine development. LGH’s institution (RC2NB) was contracted by WHO for the development of study protocol templates to evaluate public health and social measures; LGH received travel support from WHO; no other relationships or activities that could appear to have influenced the submitted work.

Figures

Fig 1
Fig 1
Flow of participants through trial
Fig 2
Fig 2
Prespecified subgroup analysis on the intervention effect of wearing surgical face masks
None
See this image and copyright information in PMC

Comment in

References

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