Coronavirus (356) Advice on the use of masks in the context of COVID-19

7 April, 2020

Below are extracts from new guidance from WHO. These extracts do not give the full picture. However, my interpretation is that the new guidance largely reinforces advice previously given by WHO, namely that 'there is currently no evidence that wearing a mask (whether medical or other types) by healthy persons in the wider community setting, including universal community masking, can prevent them from infection with respiratory viruses, including COVID-19'.

Please consult the full guidance here: https://www.who.int/publications-detail/advice-on-the-use-of-masks-in-th...(2019-ncov)-outbreak

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This document provides advice on the use of masks in communities, during home care, and in health care settings in areas that have reported cases of COVID-19...

Current information suggests that the two main routes of transmission of the COVID-19 virus are respiratory droplets and contact...

Current evidence suggests that most disease is transmitted by symptomatic laboratory confirmed cases...

In a small number of reports, pre-symptomatic transmission has been documented through contact tracing efforts...

Thus, it is possible that people infected with COVID-19 could transmit the virus before symptoms develop...

In this document medical masks are defined as surgical or procedure masks...

Wearing a medical mask is one of the prevention measures that can limit the spread of certain respiratory viral diseases, including COVID-19. However, the use of a mask alone is insufficient to provide an adequate level of protection, and other measures should also be adopted. Whether or not masks are used, maximum compliance with hand hygiene and other IPC measures is critical to prevent human-to-human transmission of COVID-19...

Community settings

Studies of influenza, influenza-like illness, and human coronaviruses provide evidence that the use of a medical mask can prevent the spread of infectious droplets from an infected person to someone else and potential contamination of the environment by these droplets.

There is limited evidence that wearing a medical mask by healthy individuals in the households or among contacts of a sick patient, or among attendees of mass gatherings may be beneficial as a preventive measure.

However, there is currently no evidence that wearing a mask (whether medical or other types) by healthy persons in the wider community setting, including universal community masking, can prevent them from infection with respiratory viruses, including COVID-19.

Medical masks should be reserved for health care workers.

The use of medical masks in the community may create a false sense of security, with neglect of other essential measures, such as hand hygiene practices and physical distancing, and may lead to touching the face under the masks and under the eyes, result in unnecessary costs, and take masks away from those in health care who need them most, especially when masks are in short supply.

Persons with symptoms should:

• wear a medical mask, self-isolate, and seek medical advice as soon as they start to feel unwell...

All persons should... [no comment on masks]

In some countries masks are worn in accordance with local customs or in accordance with advice by national authorities in the context of COVID-19. In these situations, best practices should be followed about how to wear, remove, and dispose of them, and for hand hygiene after removal.

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...

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...

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...

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Best wishes, Neil

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HIFA profile: Neil Pakenham-Walsh is coordinator of the HIFA global health campaign (Healthcare Information For All - www.hifa.org ), a global community with more than 19,000 members in 177 countries, interacting on six global forums in four languages in collaboration with WHO. Twitter: @hifa_org FB: facebook.com/HIFAdotORG neil@hifa.org