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Three Part Question

In [the general population] can [homemade from household materials or cloth face masks] prevent [respiratory virus transmission or clinical illness]?

Clinical Scenario

Since the outbreak of COVID-19, there is a worldwide shortage in protective
masks such as surgical and filtering facepiece (FFP) masks. However, your
local government advises the public to wear an alternative protective mask,
such as a homemade made from household materials or cloth mask, to avoid virus transmission during the pandemic.
You are faced with the question whether in non-healthcare settings cloth or homemade facemasks are effective at preventing virus transmission or illness caused by viruses?

Search Strategy

Search of MEDLINE, Embase, Cochrane and the specific COVID-19 database
LitCovid for studies published until 20 March 2020. Updated search performed on 30 July 2020.
MEDLINE with Pubmed
(("Masks"[Mesh]) AND "Viruses"[Mesh] AND infection) OR (("Respiratory Protective
Devices"[Mesh]) AND "Coronavirus"[Mesh]) OR (((masks[MeSH Terms]) OR
respiratory protective devices[MeSH Terms]) AND respiratory virus[MeSH Terms])
OR (home made protection masks) OR (("Masks/standards"[Mesh]) AND
"Pandemics"[Mesh]) OR (("Masks/statistics and numerical data"[Mesh]) AND
"Respiratory Protective Devices"[Mesh])) OR (("Respiratory Protective
Devices"[Mesh]) AND "Cotton Fiber"[Mesh]) OR ("Masks"[Mesh] AND cotton) OR
((("Masks/standards"[Mesh]) AND "Cotton Fiber"[Mesh]) AND "Viruses"[Mesh]) OR
("Masks"[Mesh] AND nanofabric) OR ("Masks"[Mesh] AND microfiber) OR
("Masks"[Mesh] AND muslin) OR (("Respiratory Protective Devices"[Mesh]) AND
"Developing Countries"[Mesh]) OR ((("Masks"[Mesh]) AND "Influenza,
Human"[Mesh]))
Embase
(('surgical mask'/exp OR 'mask'/exp) AND ('coronavirinae'/exp OR 'droplet
infection'/exp)) OR ('cloth mask':ab,ti AND virus:ab,ti) OR ('cotton'/exp/mj AND
'respiratory tract infection'/exp/mj) OR (('cotton'/exp OR 'face mask'/exp) AND
'coronavirinae'/exp) OR ('face mask'/exp AND 'influenza virus'/exp)
Cochrane
mask in Keyword AND influenza in Keyword OR respiratory infection in Keyword
LITCOVID
cloth masks

Search Outcome

Our search yielded 848 articles (436 MEDLINE, 320 Embase, 76 Cochrane, 13 LITCOVID and 3 snowballing), of which 830 were excluded after screening of abstracts and another 11 were excluded because they did not meet the inclusion criteria after full text review. An updated search for articles published between 20 March, 2020 and 30 July, 2020 yielded another 585
articles (160 MEDLINE, 377 Embase, 24 Cochrane, 24 LITCOVID), of which 580 were excluded after screening of abstract.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses

Comment(s)

Currently, there is no direct high-quality evidence to support widespread use of cloth masks to prevent the transmission of viral infections such as SARS-Cov-2 in the general public. All the studies we identified evaluated the use of cloth masks either in simulated settings or by healthcare personnel instead of the general public. Some small in-vitro studies have shown that cloth masks may prevent the penetration of particles smaller than 100 nm and that non-woven industrial fabrics were less penetrable for nanoparticles than cotton. However, household materials such as cotton and cotton-polyester blend were mostly permeable for virus-sized particles. Cloth masks worn when performing a variety of tasks such as nodding, reading, shaking and walking protected from particle penetration in a simulation study, but they performed worse than surgical masks and FFP2 masks. The effects found in this simulation study may not be generalizable to the general public where supervision on correct handling of face masks is lacking. One cluster randomised trial demonstrated that healthcare personnel using cloth face masks had higher rates of clinical respiratory illness, influenza-like illness and laboratory confirmed viruses compared to healthcare workers that did not routinely wear protective masks. These findings in a high-risk setting may not be applicable to the general public at lower risk of infection. However, our search did not find any studies that evaluated the effects of cloth masks on similar outcomes in the general public. Consequently, it is difficult to determine whether homemade or cloth masks offer any clinical protection for viral infections in the general public. Further research is needed to inform policy decisions on the widespread use these preventive measures during pandemics.

Clinical Bottom Line

There is currently no direct evidence to support the use of homemade or cloth masks by the general public for protection against viral infections.

References

1. MacIntyre A cluster randomised trial of cloth masks compared with medical masks in healthcare workers
2. MacIntyre Facemasks for the prevention of infection in healthcare and community settings
3. Davies Testing the Efficacy of Homemade Masks: Would They Protect in an Influenza Pandemic?
4. van der Sande Professional and Home-Made Face Masks Reduce Exposure to Respiratory Infections among the General Population.
5. Rengasamy Simple Respiratory Protection—Evaluation of the Filtration Performance of Cloth Masks and Common Fabric Materials Against 20–1000 nm Size Particles
6. Shakya Evaluating the efficacy of cloth facemasks in reducing particulate matter exposure.
7. Golanski Experimental evaluation of personal protection devices against graphite nanoaerosols: fibrous filter media, masks, protective clothing, and gloves.
8. Konda Aerosol Filtration Efficiency of Common Fabrics Usd in Respiratory Cloth Masks.
9. Ho Medical masks versus cotton mask for preventing respiratory droplet transmission in micro environments.
10. Zangmeister Filtration Efficiencies of Nanoscale Aerosol by Cloth Mask Materials Used to Slow the Spread of SARS-CoV-2.
11. Lustig Effectiveness of Common Fabrics to Block Aqueous Aerosols of Virus-like Nanoparticles.
12. Zhao Household Materials Selection for Homemade Cloth Face Coverings and Their Filtration Efficiency Enhancement with Triboelectric Charging.