Cloth face masks to prevent Covid-19 and other respiratory infections

Objective to analyze scientific evidence on the efficacy of cloth masks in preventing COVID-19 and other respiratory infections. Method integrative literature review based on the following guiding question: What is the efficacy of cloth face masks in absorbing particles that cause respiratory infection? The search was conducted in eight electronic databases, without any restriction in terms of language or period. Results low coverage cloth face masks made of 100% cotton, scarf, pillowcase, antimicrobial pillowcase, silk, linen, tea towel, or vacuum bag, present marginal/reasonable protection against particles while high coverage cloth masks provide high protection. Conclusion cloth face masks are a preventive measure with moderate efficacy in preventing the dissemination of respiratory infections caused by particles with the same size or smaller than those of SARS-CoV-2. The type of fabric used, number of layers and frequency of washings influence the efficacy of the barrier against droplets.

the efficacy of cloth face masks to prevent the new coronavirus, studies seeking evidence that support preventive measures against COVID-19 are pertinent, especially those addressing the use of cloth face masks on the part of the population, which can become coresponsible in preventing the disease. Hence, this study's objective was to analyze scientific evidence of cloth masks' efficacy in preventing COVID-19 and other respiratory infections.

Method
This integrative literature review was conducted according to the following stages: identification of the study's topic and guiding question, search for studies in the databases, critical-reflexive analysis of the studies identified, interpretation and presentation of results, and review's final synthesis (11) .
Based on the Population Interest Context (PICo) (12) strategy, the following guiding question was established: The process of selecting papers and verifying their eligibility followed the recommendations provided by Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) (13) . First, the papers' Lima MMS, Cavalcante FML, Macêdo TS, Galindo-Neto NM, Caetano JA, Barros LM titles and abstracts were read to select the papers that meet the inclusion criterion. Then, the studies selected were completed analyzed using a semi-structured instrument, which recorded the papers' title, authors, year, country, methodological characteristics, and main results. Note that three independent researchers conducted the search and selected the studies to check for potential divergences.
Level of evidence was established as follows: level I referred to meta-analyses and controlled and randomized trials; level II to experimental studies; level III to quasi-experimental studies; level IV to nonexperimental descriptive or qualitative studies; level V to experience reports; and level VI referred to expert opinion and consensus (14) .
This study complies with the ethical and legal principles provided by Resolution 510/2016, Brazilian Council of Health, concerning studies using information in the public domain.

Results
A total of 3,541 studies were identified, 3,447 of which were excluded for not meeting the inclusion criterion, and 84 were excluded for appearing more than once. Hence, nine studies remained in the final sample, as shown in Figure 1.

Studies identified in the databases n=3,541
Studies selected after reading title and abstract n=3,447 The studies selected were read and analyzed for eligibility n=10 Studies included in this review n=9 Duplicated studies that were excluded n=84 Studies excluded for not addressing the topic n=3,437 Study excluded after reading title and abstract for not addressing the efficacy of cloth masks n=1  respectively. Regarding the methodological design, there was one cluster-randomized trial (11.1%), one study adopted the mathematical analysis method proposed by Kermack-McKendrick (11.1%), and seven studies adopted laboratory tests (77.7%). Figure 2 presents the nine studies selected according to author, year, country, and methodological aspects.

Authors Year/Country Method Level of Evidence
Rengasamy; Eimer; Shaffer (15) 2010/United States Laboratory analysis: the performance of ordinary cloth material to filter nano-size particles was tested for monodisperse and polydisperse aerosols (20-1000 nm), at two different face speeds (5.5 and 16.5 cm s -1 ) and compared with the penetration levels for N95 respirator filter media.

VI
Davies, et al (16) 2013/Portugal Laboratory analysis: various domestic materials were tested regarding their ability to block bacterial and viral aerosols. The number of microorganisms isolated from the cough of healthy volunteers using homemade masks, surgical masks, or no masks, was compared using air-sampling techniques.

Maclntyre, et a l(17 ) 2015/Vietnam
Cluster-randomized clinical trial: the participants wore masks in all the working shifts for four consecutive weeks and researchers analyzed particles filtered in the surface of each mask.

2016/Nepal
Laboratory analysis: the efficiency of four types of masks in absorbing five sizes of monodisperse aerosols particles (30, 100, and 500 nm and 1 and 2.5 μm) was tested.

Neupane, et a l(19 ) 2019/Nepal
Laboratory analysis: the surface of 20 types of cloth masks was characterized using the optical image analysis method. The efficiency of the selected cloth face masks was verified using the particle counting method.   Figure 3. Table 1 presents comparisons between types of masks and their efficacy and percentage of findings. The "low protection" efficacy level included papers reporting insufficient particle filtering; "moderate protection" included papers reporting marginal/reasonable particle filtering, and the "high protection" level included papers reporting significant particle filtering. The masks significantly decreased the number of microorganisms expelled, however, surgical masks are three times more efficient in blocking spreading compared to homemade masks.
Maclntyre, et al (17) Surgical and cloth face masks Not reported The penetration of particles in cloth masks was almost 97% and 44% in surgical masks. Moisture retention, reuse of cloth masks, and insufficient filtration may result in an increased risk of infection.
Shakya, et al (18) Cloth face masks with an exhaust valve, commercially available face cloth masks, surgical and N95 masks.
Cloth face masks are marginally beneficial to protect individuals against particles <2.5 μm.

Not reported
Wearing masks in public is very useful to minimize community spreading and burden of COVID-19, provided that the coverage level is high. To decrease contamination, multi-layer cloth face masks are necessary in association with social distancing.
Particles (0 to 0.8 μm) Single-layer fabric blocked ultrafine particles. Significantly more ultrafine particles were filtered when fabric layered. Double-layered textiles were as efficient as surgical masks/fabric in decreasing droplet dispersion to <10 cm and circumferential contamination area to ~0.3%.
Ma, et al (10) One-layer polyester fabric masks, homemade face mask made of one-layer polyester fabric plus four-layer kitchen paper towel, surgical mask, and N95 mask.
Aerosols (median diameters of 3.9 μm) N95, surgical and homemade masks made of four-layer kitchen paper towel and one-layer fabric potentially block 99.98%, 97.14%, and 95.15% of the virus by aerosol, respectively.
Moderate protection 1 (100%) Davies, et al (16) Mask made of HEPA* washable vacuum bag, thick felt wool, cotton, heavy fabric, folded sock, cotton quilt, felt craft, 100% nylon, denim, cotton jersey mesh, lycra, fusible interface, and lightweight shirt. This was a measure of urgency taken in the process of preventing COVID-19 because personal protection equipment is scarce worldwide, and surgical and N95 masks should be saved for health workers who are more exposed to contamination by SARS-CoV-2.  (17) .
In the context of a pandemic, the use of cloth face masks by the population is valid considering that scientific evidence shows its efficiency, especially when they have high coverage (28) . Additionally, according to the study developed in the USA, a combination of low-efficiency face masks combined with other preventive measures, especially social isolation, favor the control of the pandemic (20) .
As for the correct use of masks, the study conducted in Nepal shows that the efficacy of cloth masks decreases 20% after the fourth washing and drying cycle (19) . This decreased efficiency occurs because the cleaning process diminishes the microfibers in the fabric and increases the size of the pores. These data contradict ANVISA's recommendations, which indicates up to 30 washing cycles (7) . Note that the WHO encourages the use and care of cloth masks, but does not restrict the number of washing cycles (8)  Most cloth masks presented moderate absorption of micrometric and nanometric particles so that we can infer that the filtering efficacy observed in these studies will be similar to viral particles causing COVID-19.
Therefore, we believe this protective equipment Another recommendation is to discard and replace masks after the fourth washing cycle.