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What is the efficacy of standard face masks compared to respirator masks in preventing COVID-type respiratory illnesses in primary care staff? – a lay summary

Standard surgical face masks are loose-fitting, while respirator masks (known in the USA as N95 and in the UK as a Filtering Face Piece or FFP mask) are designed to fit closely to the user’s face and be more efficient at filtering out tiny airborne particles and droplets. There are concerns over the risk posed by shortages of personal protective equipment (PPE) for health care staff, so this review wanted to see whether having to use standard surgical masks could pose a hazard to those who cannot access respirator masks.

Most real-world research comparing standard face masks with respirator masks has been in the context of influenza and other respiratory conditions, and based in hospitals – not in community settings. And no head-to-head studies comparing different kinds of masks have yet been published about use in COVID-19. So, there is a shortage of evidence. But what we can be reasonably certain of so far is:

  • COVID-19 is spread when droplets or tiny airborne particles coughed or sneezed by an infected person come into contact with a mucosal surface – usually the inside of somebody’s nose, mouth or the surface of their eye. The infected droplets or particles either travel through the air, or they can land on a surface and be picked up when somebody touches the surface, then their face. There is some evidence that particles landing on a surface can become airborne again when disturbed.
  • Neither type of mask prevents all infection. When caring for an infected person, the masks must be used in combination with other personal protective measures including aprons or gowns, goggles or face shields, and gloves. Users should be properly trained in how to put on and remove protective clothing in ways that minimize the chance of contamination, and to apply general infection control measures such as effective handwashing, tying back hair and removing jewellery.
  • Both types of mask are disposable and should be used only once then thrown away very carefully.
  • The standard surgical mask stops splashes and droplets coming into contact with the wearer’s nose and mouth. It fits fairly loosely to the user’s face, and should be changed if it becomes moist or damaged.
  • Guidelines currently recommend respirator masks, with their close fit and finer weave, for greater protection against exposure to airborne particles – very small particles that can carry infectious agents, remaining in the air for long periods of time and being carried over long distances by air currents. Airborne particles can be released in coughs and sneezes, and during certain medical procedures.
  • However, studies comparing standard surgical with respirator masks, when used with other recommended protective clothing by healthcare staff caring for patients with a variety of influenza-like viral illnesses, found no real differences between the ability of the two types of mask to prevent spread of the diseases.

Mandy Payne, 31 March 2020

This is a lay summary of a report repared for the Oxford COVID-19 Evidence Service of the Oxford Centre for Evidence Based Medicine, Nuffield Department of Primary Care Health Sciences, University of Oxford by Trish Greenhalgh, Xin Hui Chan, Kamlesh Khunti, Quentin Durand-Moreau, Sebastian Straube, Declan Devane, Elaine Toomey and Anil Adisesh, and posted on 24th March 2020, updated 30th March 2020.

Disclaimer: the article has not been peer-reviewed; it should not replace individual clinical judgement and the sources cited in the original report should be checked. The views expressed in this commentary represent an interpretation by HealthWatch and do not necessarily represent those of Oxford CEBM, the NHS, the NIHR, or the Department of Health and Social Care. The views are not a substitute for professional medical advice.


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