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Advice to decision makers on the use of masks for healthy people in community settings
As described above, the wide use of masks by healthy people in the community setting is not supported by current evidence and carries uncertainties and critical risks. WHO offers the following advice to decision makers so they apply a risk-based approach.
Decisions makers should consider the following:
1. Purpose of mask use: the rationale and reason for mask use should be clear– whether it is to be used for source control (used by infected persons) or prevention of COVID-19 (used by healthy persons)
2. Risk of exposure to the COVID-19 virus in the local context:
- The population: current epidemiology about how widely the virus is circulating (e.g., clusters of cases versus community transmission), as well as local surveillance and testing capacity (e.g., contact tracing and follow up, ability to carry out testing).
- The individual: working in close contact with public (e.g., community health worker, cashier)
3. Vulnerability of the person/population to develop severe disease or be at higher risk of death, e.g. people with comorbidities, such as cardiovascular disease or diabetes mellitus, and older people
4. Setting in which the population lives in terms of population density, the ability to carry out physical distancing (e.g. on a crowded bus), and risk of rapid spread (e.g. closed settings, slums, camps/camp-like settings).
5. Feasibility: availability and costs of the mask, and tolerability by individuals.
6. Type of mask: medical mask versus nonmedical mask (see below).
In addition to these factors, potential advantages of the use of mask by healthy people in the community setting include reducing potential exposure risk from infected person during the “pre-symptomatic” period and stigmatization of individuals wearing mask for source control.
However, the following potential risks should be carefully taken into account in any decision-making process:
• self-contamination that can occur by touching and reusing contaminated mask
• depending on type of mask used, potential breathing difficulties
• false sense of security, leading to potentially less adherence to other preventive measures such as physical distancing and hand hygiene
• diversion of mask supplies and consequent shortage of mask for health care workers
• diversion of resources from effective public health measures, such as hand hygiene
Whatever approach is taken, it is important to develop a strong communication strategy to explain to the population the circumstances, criteria, and reasons for decisions. The population should receive clear instructions on what masks to wear, when and how (see mask management section), and on the importance of continuing to strictly follow all other IPC measures (e.g., hand hygiene, physical distancing, and others).
Type of Mask
WHO stresses that it is critical that medical masks and respirators be prioritized for health care workers.
The use of masks made of other materials (e.g., cotton fabric), also known as nonmedical masks, in the community setting has not been well evaluated. There is no current evidence to make a recommendation for or against their use in this setting.
WHO is collaborating with research and development partners to better understand the effectiveness and efficiency of nonmedical masks. WHO is also strongly encouraging countries that issue recommendations for the use of masks in healthy people in the community to conduct research on this critical topic. WHO will update its guidance when new evidence becomes available.
In the interim, decision makers may be moving ahead with advising the use of nonmedical masks. Where this is the case, the following features related to nonmedical masks should be taken into consideration:
• Numbers of layers of fabric/tissue
• Breathability of material used
• Water repellence/hydrophobic qualities
• Shape of mask
• Fit of mask