Question & Answer

Does wearing a face-mask by people who are not sick prevent COVID-19 infection?

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  • Guidance about whether people who are not sick should wear masks is not always clear, and different guidelines do not always align or agree completely. Evidence in this area is limited and inconclusive. In the absence of good quality, conclusive evidence, the potential benefits of widespread mask-wearing must be weighed against the potential harms.
  • The evidence suggests that wearing a mask reduces the amount of droplets scattered from the nose and mouth, and acts as a ‘source control’ to protect the environment/others from the wearer. There is general agreement from the WHO, US CDC and other organisations that people with respiratory symptoms (including coughing and sneezing) should wear face coverings in combination with other measures (e.g. self-isolation, hand hygiene, respiratory etiquette etc) to help prevent spread of COVID-19.
  • There is increasing evidence suggesting that people who have COVID-19, but who have mild or no symptoms, may contribute to the spread of COVID-19. It is plausible that using face coverings in combination with other measures may help reduce the spread of infection in the community by individuals who may not even know they are infected and have not yet developed any symptoms. This may be particularly important for situations where it is difficult to practise social distancing or in enclosed indoor spaces, e.g. in shops, attending a GP practice or using public transport.
  • There are a number of potential risks of wearing masks that need to be carefully considered. These include:
    • self-contamination from touching and reusing a contaminated mask
    • potential difficulties with breathing or communication
    • a false sense of security leading to potentially less adherence to other preventive measures such as physical distancing and hand hygiene
    • diversion of mask supplies leading to a shortage of masks for health care workers
    • diversion of resources from effective public health measures, such as hand hygiene
  • Very few studies have been conducted on SARS-CoV-2/COVID-19, or in widespread community settings. Studies are often small or poor quality, the type of mask used in studies (e.g. medical/homemade face coverings) is often varied or unclear, and adverse effects or unintended consequences (such as self-contamination) are rarely reported.
  • It is unclear whether the use of masks or face coverings is linked to lower COVID-19 rates seen in some countries (e.g. China, Singapore, South Korea and Japan) because mask use is only one of many response measures that have been applied in these countries. Additionally, important factors influencing mask use such as following instructions regarding use, cultural/social norms, respiratory etiquette and hand hygiene practices may be different and not generalisable to other countries.
  • Medical masks are not recommended for use by the public, as this may result in fewer being available for healthcare workers. As such, where masks are to be used by the public, these should be non-medical face masks or other face covers made from materials such as cotton and silk. It is unclear whether this guidance differs for people with and without symptoms. However, the use of non-medical masks/homemade face coverings has been very poorly evaluated and there are no established standards for non-medical masks. To avoid confusion, the term ‘face covering’ is used in some guidance for non-medical masks
  • Face coverings alone are not sufficient to prevent spread of COVID-19. They are NOT a replacement for other recommended measures e.g. hand hygiene, respiratory etiquette, social distancing etc, and must be supported by adequate training on how to safely use face coverings (including how to put them on and take them off safely) before wearing them.
  • Face coverings may not be appropriate for some people(e.g. children under 13, people who have breathing difficulties or are unable to remove the covering without assistance).
  • Research in this area is rapidly evolving, and it is expected that recommendations will continue to evolve accordingly.

Things to Remember

Reviewers

  • Lead Researcher: Dr Elaine Toomey, School of Allied Health, University of Limerick & Cochrane Ireland Research Associate
  • Reviewed by: Prof Declan Devane, School of Nursing and Midwifery, HRB-Trials Methodology Research Network, Evidence Synthesis Ireland & Cochrane Ireland, NUI Galway
  • Evidence Advisor: Prof Liam Glynn, School of Medicine, University of Limerick
  • Evidence Advisor: Deirdre Mac Loughlin, PPI Ignite, NUI Galway
  • Journalist Advisor: Dr Claire O’Connell, Journalist, Contributor, The Irish Times