Wearing a surgical face mask in public spaces reduces the risk of self-reported respiratory symptoms, finds a trial of adults in Norway published by The BMJ today. The effect was moderate - a 3.2% reduction in symptoms, equivalent to around 3,300 fewer infections per 100,000 people - but the researchers say these results support the claim that face masks may be an effective measure to reduce the rate of self-reported symptoms consistent with respiratory tract infections.
Observational studies suggest that face masks reduce the risk of respiratory tract infections, but findings from randomised trials are inconclusive. To explore this further, the researchers carried out a randomised controlled trial 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. Their findings are based on data from 4,575 adults in Norway (average age 51; 61% women) between 10 February 2023 and 27 April 2023, during a normal influenza season in the Nordic countries.
Participants completed an online questionnaire about sociodemographic and lifestyle factors, beliefs about face masks and risk of infection, and face mask use in the two weeks before the study. Some 2,313 participants were then randomly assigned to wear a disposable surgical face mask when close to people in public spaces (eg, shopping centres, streets, public transport) over 14 days (intervention arm) and 2,262 were asked to .