Efficacy of cloth face mask in prevention of novel coronavirus infection transmission: A systematic review and meta-analysis
Suresh K Sharma1, Mayank Mishra2, Shiv K Mudgal1
1 College of Nursing, All India Institute of Medical Sciences, Rishikesh, Uttarakhand, India
2 Department of Pulmonary Medicine, All India Institute of Medical Sciences, Rishikesh, Uttarakhand, India
|Date of Submission||19-May-2020|
|Date of Acceptance||11-Jun-2020|
|Date of Web Publication||28-Jul-2020|
Prof. Suresh K Sharma
College of Nursing, All India Institute of Medical Sciences, Rishikesh - 249 203, Uttarakhand
Source of Support: None, Conflict of Interest: None
INTRODUCTION: Novel coronavirus is believed to be tiny enough (0.08–0.14 μm) to penetrate through face mask, thus protection offered by cloth mask may be too low. However, the use of cloth face mask in community has been recommended by the United States Centre for Disease Control and Prevention and regulatory bodies of other countries. There is paucity of literature on efficacy of cloth face mask in preventing SARS-CoV-2 infection transmission; thus, this review aims to update the available most recent evidences on efficacy of cloth face masks in prevention of viral infection transmission.
METHODS: We searched MEDLINE, EMBASE, and Clinical Trials Register for identifying studies related to this review using free-text terms and MeSH terms. Both experimental and observational studies on efficacy of cloth masks which were published in English language have been included in this review except expert opinions, commentaries, editorials, and review articles. Twelve studies were eligible to be included in review for data extraction and qualitative synthesis was carried out from extracted data but quantitative analysis (meta-analysis) could not be performed because of serious heterogeneity between the studies.
RESULTS: Cloth face masks show minimum efficacy in source control than the medical grade mask. The efficacy of cloth face masks filtration varies and depends on the type of material used, number of layers, and degree of moisture in mask and fitting of mask on face.
CONCLUSION: Cloth face masks have limited efficacy in combating viral infection transmission. However, it may be used in closed, crowded indoor, and outdoor public spaces involving physical proximity to prevent spread of SARS-CoV-2 infection.
Keywords: COVID-19, face masks, homemade mask, viral infection
|How to cite this article:|
Sharma SK, Mishra M, Mudgal SK. Efficacy of cloth face mask in prevention of novel coronavirus infection transmission: A systematic review and meta-analysis. J Edu Health Promot 2020;9:192
|How to cite this URL:|
Sharma SK, Mishra M, Mudgal SK. Efficacy of cloth face mask in prevention of novel coronavirus infection transmission: A systematic review and meta-analysis. J Edu Health Promot [serial online] 2020 [cited 2020 Oct 20];9:192. Available from: https://www.jehp.net/text.asp?2020/9/1/192/290942
| Introduction|| |
The use of face mask is quite common among people of Asian Countries such as South Korea, Japan, China, and Thailand; pollution or earlier outbreaks of respiratory illnesses such as SARS and H1N1 could be the reason for this practice of mask usage. The current outbreak of COVID-19 is devastating and China dictated that everyone must wear face mask but also recommended use of cloth face mask for people at very low risk of contracting and spreading infection.
The United States Centre for Disease Control and Prevention also recommended cloth face covering especially in areas of significant community-based transmission and discouraged people to use surgical face mask to prevent their irrational usage that could potentially cause a serious shortage for frontline health-care workers (HCWs) who actually need it. On similar lines, countries such as the United Kingdom, New Zealand, and Singapore specifically urged people not to use surgical face mask to procure enough supplies in stock for HCWs.
Countries such as the Czech Republic, Slovakia, Austria, Morocco, Turkey, Poland, Jamaica, Germany went a step further in their attempt to curb virus spread, mandating the use of face masks, with citizens facing penalties if caught barefaced. India acted in accordance to situation and followed a modest approach and advised people to wear homemade cloth mask along with meticulous hand hygiene to prevent transmission of the novel corona virus (SARS-CoV-2).
SARS-CoV-2 primarily spreads through droplet and contact transmission;, however, the risk of airborne transmission remains questionable and requires additional empirical data for confirmation., Droplet and contact methods are considered as predominant modes for transmission of SARS-CoV-2 but reports still present conflicting data about universal use of face mask to curb such transmission.
COVID-19 is a pandemic, which people are struggling to combat worldwide and countries are facing scarcity of resources especially medical grade masks (surgical masks, N95, and other necessary respirators). In such situation, it is important that policymakers look for other options to maintain or balance the chain of demand and supply to minimize infection transmission. Therefore, it is crucial at this point to know the efficacy of cloth face masks as an alternative for medical masks for the prevention of SARS-CoV-2 infection.
Amidst current knowledge gaps, evidence-based answer is urgently required for a critically important question, i.e., does the cloth face mask help curb SARS-CoV-2 transmission? To meet this important need of the hour, we present this comprehensive, rapid evidence-based review to answer the aforesaid question.
| Methods|| |
Using PRISMA guidelines, we searched MEDLINE, EMBASE, Cochrane Library, and Clinical Trials Register for identifying studies related to this Review. Free-text terms and Mesh terms such as “masks” OR “respiratory protective devices” AND “COVID-19,” “masks” OR “mask” AND “(cloth OR fabric OR homemade OR home-made)” “virus diseases,” “respiratory AND “virus diseases “AND “mask” “masks,” and “respiratory protective devices” or “masks” AND “respiratory tract infections” were used for the purpose. Two reviewers carried out the search, examined the eligibility of the studies independently. We also reviewed cross-references cited in retrieved articles to identify additional relevant studies. The discrepancy among the two reviewers was resolved through discussion with the primary reviewer.
We selected studies, which were fulfilling the following criteria:
- Studies examining cloth face mask filtration effectiveness
- Studies examining cloth face mask efficacy in clinical and community settings
- Studies published in English language
- All experimental and observational studies till the date of search.
We excluded the following studies or papers:
- Case reports, letters, editorials, opinions
- Review papers.
Data regarding selected variables were extracted from each included study as per objective of this review, including the filtration efficacy of cloth face masks and clinical outcomes. Finally, 12 articles [Figure 1] were found suitable for consideration in writing this comprehensive evidence-based rapid review.
Assessment of risk of bias
Risk of bias for the included randomized controlled trials was assessed using the risk of bias Tool version 2 by the Cochrane Collaboration. Two independent authors carried out risk of bias assessment. The summary of risk of bias is presented in [Figure 2]. Quality of the observational studies was assessed on the basis of STROBE guidelines and mentioned in respective summary table.
Data synthesis and analysis
The data were categorized and tabulated based on review objectives. The meta-analysis could not be done because of clinical and methodological heterogeneity among included studies. Therefore, narrative summary approach was used for data synthesis.
| Results|| |
We performed literature search till May 10, 2020, as per PRISMA guideline [Figure 1]. A total of 861 studies were identified using different data bases (PubMed-323, EMBASE-378, Cochrane Library and Clinical Trial-127 and 25, respectively, while 8 studies were from other sources). We identified 12 studies,,,,,,,,,,,, which fulfilled eligibility criteria of our review. Among them, nine studies were non-clinical trials, one study was nonrandomized controlled trial, and other two studies were randomized controlled trials [Table 1] and [Table 2].
|Table 1: Summary of interventional studies on efficacy of cloth face masks versus medical grade masks for prevention of viral infection transmission|
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|Table 2: Summary of observational studies on efficacy of cloth face masks versus medical grade masks for prevention of viral infection transmission|
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There is no published randomized controlled trial to advocate mask usage as an effective strategy for control of SARS-CoV-2 transmission, although various studies have tried to indirectly assess the efficacy of masks against spread of various respiratory infections. A review has also demonstrated the use of hand washing as an additional practice to mask users that may decrease the dissemination of respiratory viral infection.
An evidence-based review recommended that practice of wearing cloth mask is an effective strategy for SARS-CoV-2 infection control in conjunction with social distancing, hand hygiene, and contact tracing measures. The evidences from various studies and recommendations of different organizations suggested that cloth masks are not ideal, but in the present situation of COVID-19 pandemic, where some countries are facing shortage of N95 or surgical masks, the only option left is to use cloth masks and they may be effective in preventing infection transmission. The Institute of Medicine (IOM) acknowledged the probable reliance on cloth masks during an influenza pandemic and recommended the need for further research on the use of cloth masks. [Table 1] and [Table 2] show the role of homemade masks in clinical efficacy,, filtration efficacy in laboratory setup,,,,,,,,,, effect of leakage on masks efficacy, and compliance.
The SARS-CoV-2 virus particle is very tiny (0.08–0.14 μm), therefore, tightly woven cotton fabric such as towel, scarves, cotton sheets, quilt or T-shirt fabric were also recommended for making cloth mask to improve its virus filtration efficacy, comfort, and enhanced moisture regain (7%–11%).,, Additional features to enhance the filtration efficiency of cloth masks may be a snug fit mask with minimal leak and use of three-layered mask with middle layer made of nonwoven breathable filter of anti-microbial finish, like coffee filter., Strict adherence to mask wearing, regular washing with detergent and disinfection in sunlight is essential for achieving enhanced efficacy of cloth face mask. A brief summary on efficacious use of cloth mask is presented in [Table 3].
| Discussion|| |
Although there is lack of strong empirical evidence on efficacy of cloth face masks; however, available literature reports a lower level of efficacy of cloth facemask in reducing the risk of contracting viral infections.,, Furthermore, filtering efficiency of cloth face mask is seriously affected by risk of poor facial fitting of cloth masks, which is further lowered by repeated washing and drying cycle. Studies have reported that filtration efficacy of cloth masks is strongly affected by various factors such as type of cloth, layers of cloth in mask, combination of different types of cloths, leakage of air around mask, and degree of moisture in mask. Three or more layers of cotton cloth mask in combination with either silk, chiffon, or flannel which is well-fitted on face with minimal or no leak of air around mask and having no moisture provides the best possible protection against viral infection.,,,,
Studies have stated that cloth face masks are ineffective to prevent influenza-like diseases when compared to the surgical masks (relative risk 13.25, 95% confidence interval [CI] 1.74–100.97). Moreover, filtration efficacy of cloth face mask was found as low as 3% on laboratory based filtration test of cloth masks, which could be because of poor quality of cloth used for making face mask.
Surprisingly, one of the studies reported no relationship between compliance rate of cloth face mask and rate of infection; which raises doubts on whether the use of mask has any role in prevention of risk for contracting the viral infection. However, these findings were contradictory to the findings of a systematic review and meta-analysis published in 2011. This review presented the results of seven case–control studies and reported that the odds ratio of group using cloth masks versus control group was 0.32 (95% CI, 0.26–0.39) on rate of respiratory viral infection.
Filtering efficiency of cloth face masks is low as compared to surgical and 95 masks and it may be further affected by several other factors. First, small number of aerosols passing through the cloth mask may be enough in number to make a person infected. Another probability is that, the leakage around the cloth masks may significantly reduce its efficiency and studies also reported that leakage may decrease nearly 50% of masks efficacy., However, these problems may also be related to medical grade masks and affects their efficiency. Cloth masks are routinely washed and dried and used for a long time while surgical masks disposed after single use. However, one study reported that washing and drying repeatedly may deteriorate the quality and efficacy of the cloth masks, by nearly 20% after four times of this cycle.
The cotton cloth face masks which are made up of multiple alternative layers of cotton and any of these-silk, chiffon, or flannel fabric that are well fitted on face to ensure minimal or no leak may provide filtration efficacy as high as >90%. The two-layered cotton fabric face mask with 240 threads per centimeter reported a filtering efficiency of 99.5 ± 0.1%; which is close to that of N95 masks (99.9% ± 0.1%) for >300 nm size particle.
There is lack of strong well-designed evidences on efficacy of cloth face mask in the prevention of viral infections and moreover, the findings are conflicting on some aspects such as quality of cloth, design of mask, fitness on face, compliance, and other factors. The compliance of wearing a face mask is as low as <50% and it may be due to feeling of suffocation and hindrance in communication.
Cloth face mask is less efficacious as compared to surgical mask and N95 masks; they must be preserved for the frontline health-care providers and high risk people. Therefore, cloth face mask maybe used by people in high-risk situations like closed, crowded public spaces where there is high risk of close physical proximity with other people. However, wearing face mask may give a false sense of security to the wearer, which may contribute to low hand hygiene compliance, poor respiratory etiquettes, breaching norms of social distancing, and risk of repeated touching of nose and face to adjust the face mask. Therefore, people must be educated that cloth face mask should be used as complimentary measure of infection prevention along with meticulous hand washing, social distancing, respiratory etiquettes and avoid touching nose, face, or mask without hand washing.
Study limitations and novelty
This review paper discussed the efficacy of cloth face masks in prevention of infection caused by viruses in hospital and community settings. With authors' best knowledge, this review included highest numbers of studies to make a conclusion on the same subject.
We did not find any study, which compares the efficacy of cloth masks in the prevention of SARS-CoV-2 infection. Furthermore, only two randomized controlled trials were included that examined the efficacy of different masks. However, one of them was under powered and conducted among four participants. Because of the rapidity of this article, we were not able to search other databases or article archives such as CINAHL, Google Scholar, and ClinicalTrial.gov.
| Conclusion|| |
Cloth face masks are less efficacious as compared to medical grade masks; however, something is better than nothing; therefore, it may be transiently used in closed, crowded indoor, and outdoor public spaces during highly contagious viral pandemics like COVID-19. However, the importance of meticulous hand hygiene, respiratory etiquettes, social distancing (>2 meters), and avoidance of repetitively touching one's face, nose, eyes, and mouth as basic measures to prevent SARS-CoV-2 transmission cannot be overemphasized. Nonetheless, the cloth masks are not found efficacious for infection prevention in hospital setting; therefore, its use for health-care workers should not be recommended.
The efficacy of cloth mask can be improved by multilayer cloth mask made of cotton in combination with synthetic cloth material, which has proper fitting on face, and must be regularly changed. Furthermore, a well-designed randomized controlled trial must be conducted to assess the efficacy of cloth face mask.
We are very thankful to Ms. Kalpana Thakur, Ms. Priya Sharma and Sh. Sandeep Singh for their valuable suggestions and feedback for first draft of this article.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3]