In a recent study published in BMJ, a team of Norwegian researchers conducted a pragmatic randomized trial to examine whether wearing surgical face masks while in public spaces resulted in a lower incidence of self-reported respiratory infection symptoms than not wearing a face mask.

Background

The use of surgical face masks became widespread with the onset of the coronavirus disease 2019 (COVID-19) pandemic. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) claimed close to seven million lives worldwide and infected almost 77 million people. To curb the spread of SARS-CoV-2, most countries implemented social distancing and lockdown measures and encouraged the use of personal protective gear such as face masks.

However, the results from subsequent studies on the effectiveness of face masks have been contradictory. Some observational studies report a significantly lower rate of respiratory illnesses associated with the use of face masks. In contrast, other reviews have reported that face masks have had no effect in lowering the incidence of respiratory infections due to viruses.

About the study

In the present study, the researchers conducted a pragmatic randomized trial to determine whether people who wore face masks for 14 days while they were in public spaces had a lower rate of self-reported symptoms of respiratory infections as compared to people who did not wear face masks in similar situations.

The study was conducted between February and April 2023, with the period being the COVID-19 pandemic’s most acute phase in Norway and not overlapping with the influenza season. The health authorities in Norway had not implemented other social or public health measures during this period.

Individuals 18 years of age or older who were willing to be assigned randomly to the intervention or control group were eligible to participate in the study. The individuals in the intervention group were required to wear face masks for 14 days when they were near other people or in public spaces, while those in the control group were not.

The study focused only on the use of face masks and did not include filtering facepiece 3 (FFP3) respirators. The individuals in the intervention group were provided three-ply face masks free of charge, along with instructions on the appropriate use of the masks. They were required to wear masks when they were in public spaces such as streets, public transport, shopping centers, etc.

All participants were also required to fill out a questionnaire to provide sociodemographic data as well as information on lifestyle factors. The questionnaire also queried their views on the risk of infection and the use of face masks and gathered data on their use of face masks in the two weeks preceding the onset of the study.

If the participants experienced COVID-19-like symptoms, they were encouraged to consult a doctor and undergo a polymerase chain reaction (PCR) test. The primary outcome measured in the study was the incidence of self-reported symptoms indicating a respiratory infection. Positive COVID-19 PCR test results were the secondary outcome.

The primary outcome symptoms included cold or COVID-19-like symptoms, along with fever, and one respiratory symptom, such as sore throat, runny or stuffy nose, sneezing, difficulty breathing, or coughing. Other symptoms included muscular or body aches, reduced appetite, headache, anosmia, and fatigue.

Results

The study confirmed that the use of surgical face masks while being out around other people and in public spaces lowered the incidence of self-reported respiratory infection symptoms. Face masks were found to be an effective mode of lowering the incidence of respiratory infections.

While the risk of infection without wearing the mask was 12.2%, the use of surgical face masks lowered the infection risk to 8.9%, which translates to the prevention of 3300 infections every 100,000 people. Furthermore, face mask-wearing was well tolerated and safe, and the only adverse effects reported in the study were unpleasant remarks from passersby.

Face masks are believed to be effective in preventing respiratory infections by limiting the transmission of aerosols and droplets through which respiratory viruses spread. Other similar studies have reported a significant decrease in the rate of respiratory infections after the onset of the COVID-19 pandemic, which was also attributed to the wearing of face masks and the social distancing measures implemented to limit the spread of SARS-CoV-2.

Conclusions

Overall, the study confirmed the findings from various other studies that the use of surgical face masks while out in public spaces is effective in lowering the risk of respiratory infections. While the effect sizes of the study are moderate, given that wearing face masks has almost no adverse effects and is a low-cost intervention, the researchers recommend the use of face masks to lower the incidence of respiratory infections.