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Does Masking Matter? Cochrane Calls Masking Into Question

March 20, 2023

Written by Seth Walsh-Blackmore

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In this Cochrane review, hand-hygiene programs reduce the incidence of clinical acute respiratory illness (ARI), while masking probably does not provide additional benefit.

Why does this matter?
The benefits of preventive physical barriers may seem obvious, but no intervention should be assumed effective without evidence. COVID-19 revealed issues in enacting public health policy for which objective information is needed to guide future decision-making. So, what works?

Please wash your hands after pulling off your mask.
This is an update to the 2020 Cochrane review of this topic, which now only includes 78 RCTs, 6 during the COVID-19 era.

The most efficacious intervention was hand hygiene programs, with an overall RR of 0.86 (95%CI 0.81-0.90) for ARI incidence relative to control, but not for laboratory-confirmed influenza and influenza-like illness (ILI), RR 0.94 (0.81 -1.09). Hand hygiene also reduced absenteeism from work or school RR 0.64 (0.58 – 0.71) in a smaller subset of trials. One trial examined hand sanitizer vs. soap and water with RR 1.21 (1.06 – 1.39) for ARI with soap and water alone (hand sanitizer was better).

Surgical/procedure masks did not reduce the incidence of COVID/influenza-like illness relative to no masks RR 0.95 (0.84 – 1.09). N95/P2 respirators did not significantly reduce risk relative to standard masks RR 0.70 (0.45-1.10). No efficacy improvement was present for either comparison in lab-confirmed COVID/influenza.

Surface disinfection and physical distancing were reviewed, but heterogeneity precluded data pooling. No face shields, gowns, gloves, or entry point screening trials were included.

The results support continued hand hygiene as is already standard of practice. Though perhaps surprising, it supports the ongoing move away from mask mandates by many institutions. Note that most of the analyzed data are still pre-COVID-19. There are at least four RCTs awaiting publication and four active trials of physical interventions during this period, hopefully providing more robust data on masking and physical distancing.

Source
Physical interventions to interrupt or reduce the spread of respiratory viruses. Cochrane Database Syst Rev. 2023 Jan 30;1(1):CD006207. doi: 10.1002/14651858.CD006207.pub6.

Editor’s Note: Use of masks in community settings doesn’t seem to make a big difference. This is counterintuitive and emphasizes why we need these RCTs. However, the risk reduction for individual high risk patients, with very high mask compliance, can’t be captured in a study like this. We still have a lot to learn, but this study doesn’t support general masking. ~Clay Smith