https://wwwnc.cdc.gov/eid/article/26/10/20-0948_article
We told you all the truth... but most of you could not handle it.
Future Research Directions
More research on cloth masks is needed to inform their use as an alternative to surgical masks/respirators in the event of shortage or high-demand situations. To our knowledge, only 1 randomized controlled trial (4) has been conducted to examine the efficacy of cloth masks in healthcare settings, and the results do not favor use of cloth masks. More randomized controlled trials should be conducted in community settings to test the efficacy of cloth masks against respiratory infections. According to the US Institute of Medicine, National Academy of Sciences, more research on the engineering design of cloth masks to enhance their filtration and fit is needed (16). Moreover, various methods for decontaminating cloth masks should be tested.
Here is the abstract - notice they confusing use of "may be used"
Abstract
Cloth masks have been used in healthcare and community settings to protect the wearer from respiratory infections. The use of cloth masks during the coronavirus disease (COVID-19) pandemic is under debate. The filtration effectiveness of cloth masks is generally lower than that of medical masks and respirators; however, cloth masks may provide some protection if well designed and used correctly. Multilayer cloth masks, designed to fit around the face and made of water-resistant fabric with a high number of threads and finer weave, may provide reasonable protection. Until a cloth mask design is proven to be equally effective as a medical or N95 mask, wearing cloth masks should not be mandated for healthcare workers. In community settings, however, cloth masks may be used to prevent community spread of infections by sick or asymptomatically infected persons, and the public should be educated about their correct use.
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Here is the argument or the hope for masks...
The primary transmission routes for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are thought to be inhalation of respiratory droplets and close contact; therefore, WHO recommends wearing medical masks during routine care and using respirators during aerosol-generating procedures and other high-risk situations (17). However, SARS-COV-2 is a novel pathogen, and growing evidence indicates the possibility of airborne transmission (18–21). Recommendations to wear masks to protect the wearer from droplet infections are based on the assumption that droplets travel short distances only, generally 1–2 m. However, of 10 studies of horizontal droplet distance, 8 showed that droplets travel >2 m, in some instances ≈8 m (22). A recent study also showed that SARS-CoV-2 may be transmitted up to 4 m (18). Therefore, ideally, all frontline healthcare workers should use a respirator. However, demand for personal protective equipment has increased during the COVID-19 pandemic, and respirator shortages in previous pandemics have also been reported (23–26). If respirators are unavailable, healthcare workers could use a medical mask but may be at increased risk if they do so (2). CDC and the European Centre for Disease Prevention and Control initially recommended that all healthcare workers use respirators; however, because of shortages, they later recommended respirator use for high-risk situations only (27,28). Some countries also recommend sterilizing and decontaminating respirators for reuse; however, limited evidence supports these practices (29), and they may not be feasible in low- and middle-income countries.
During a pandemic, cloth masks may be the only option available; however, they should be used as a last resort when medical masks and respirators are not available (3). Cloth mask use should not be mandated for healthcare workers, but some may choose to use them if there are no alternatives (30). Protection is affected by proper mask use as well as by selection of fabric and design of the masks for water resistance, filtration, and fit. Current evidence suggests that multilayered masks with water-resistant fabric, high number of threads, and finer weave may be more protective (3,10). Several studies have examined filtration, but fewer have examined fit or water resistance. Surgical masks are normally rated for fluid resistance, and cloth masks should be too. Masks should be able to prevent a stream of fluid flowing at a pressure of up to 160 mm Hg from seeping through the mask and potentially into the mouth. Furthermore, the degree of fit affects effectiveness because air flows in the direction of least resistance; if gaps are present on the sides of the mask, air will flow through those gaps instead of through the mask.
Cloth masks can be made in large quantities in a short time. They can be reused after being decontaminated by various techniques, ideally washing in hot water with soap. Other methods or products include using bleach, isopropyl alcohol, or hydrogen peroxide; autoclaving or microwaving; and application of ultraviolet radiation or dry heat (16). Unlike disposable medical masks and respirators, the material of cloth masks is unlikely to degrade from standard decontamination procedures. However, hospitals will have the extra burden of cleaning and decontaminating used masks. If healthcare workers perform decontamination themselves, they may fail to wash masks frequently enough and may risk self-contamination (31).
The general public can use cloth masks to protect against infection spread in the community. In community settings, masks may be used in 2 ways. First, they may be used by sick persons to prevent spread of infection (source control), and most health organizations (including WHO and CDC) recommend such use. In fact, a recent CDC policy change with regard to community use of cloth masks (1) is also based on high risk for transmission from asymptomatic or presymptomatic persons (32). According to some studies, ≈25%–50% of persons with COVID-19 have mild cases or are asymptomatic and potentially can transmit infection to others. So in areas of high transmission, mask use as source control may prevent spread of infection from persons with asymptomatic, presymptomatic, or mild infections. If medical masks are prioritized for healthcare workers, the general public can use cloth masks as an alternative. Second, masks may be used by healthy persons to protect them from acquiring respiratory infections; some randomized controlled trials have shown masks to be efficacious in closed community settings, with and without the practice of hand hygiene (33). Moreover, in a widespread pandemic, differentiating asymptomatic from healthy persons in the community is very difficult, so at least in high-transmission areas, universal face mask use may be beneficial. The general public should be educated about mask use because cloth masks may give users a false sense of protection because of their limited protection against acquiring infection (16). Correctly putting on and taking off cloth masks improves protection (Table). Taking a mask off is a high-risk process (34) because pathogens may be present on the outer surface of the mask and may result in self-contamination during removal (31).
We told you all the truth... but most of you could not handle it.
Future Research Directions
More research on cloth masks is needed to inform their use as an alternative to surgical masks/respirators in the event of shortage or high-demand situations. To our knowledge, only 1 randomized controlled trial (4) has been conducted to examine the efficacy of cloth masks in healthcare settings, and the results do not favor use of cloth masks. More randomized controlled trials should be conducted in community settings to test the efficacy of cloth masks against respiratory infections. According to the US Institute of Medicine, National Academy of Sciences, more research on the engineering design of cloth masks to enhance their filtration and fit is needed (16). Moreover, various methods for decontaminating cloth masks should be tested.
Here is the abstract - notice they confusing use of "may be used"
Abstract
Cloth masks have been used in healthcare and community settings to protect the wearer from respiratory infections. The use of cloth masks during the coronavirus disease (COVID-19) pandemic is under debate. The filtration effectiveness of cloth masks is generally lower than that of medical masks and respirators; however, cloth masks may provide some protection if well designed and used correctly. Multilayer cloth masks, designed to fit around the face and made of water-resistant fabric with a high number of threads and finer weave, may provide reasonable protection. Until a cloth mask design is proven to be equally effective as a medical or N95 mask, wearing cloth masks should not be mandated for healthcare workers. In community settings, however, cloth masks may be used to prevent community spread of infections by sick or asymptomatically infected persons, and the public should be educated about their correct use.
====
Here is the argument or the hope for masks...
The primary transmission routes for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are thought to be inhalation of respiratory droplets and close contact; therefore, WHO recommends wearing medical masks during routine care and using respirators during aerosol-generating procedures and other high-risk situations (17). However, SARS-COV-2 is a novel pathogen, and growing evidence indicates the possibility of airborne transmission (18–21). Recommendations to wear masks to protect the wearer from droplet infections are based on the assumption that droplets travel short distances only, generally 1–2 m. However, of 10 studies of horizontal droplet distance, 8 showed that droplets travel >2 m, in some instances ≈8 m (22). A recent study also showed that SARS-CoV-2 may be transmitted up to 4 m (18). Therefore, ideally, all frontline healthcare workers should use a respirator. However, demand for personal protective equipment has increased during the COVID-19 pandemic, and respirator shortages in previous pandemics have also been reported (23–26). If respirators are unavailable, healthcare workers could use a medical mask but may be at increased risk if they do so (2). CDC and the European Centre for Disease Prevention and Control initially recommended that all healthcare workers use respirators; however, because of shortages, they later recommended respirator use for high-risk situations only (27,28). Some countries also recommend sterilizing and decontaminating respirators for reuse; however, limited evidence supports these practices (29), and they may not be feasible in low- and middle-income countries.
During a pandemic, cloth masks may be the only option available; however, they should be used as a last resort when medical masks and respirators are not available (3). Cloth mask use should not be mandated for healthcare workers, but some may choose to use them if there are no alternatives (30). Protection is affected by proper mask use as well as by selection of fabric and design of the masks for water resistance, filtration, and fit. Current evidence suggests that multilayered masks with water-resistant fabric, high number of threads, and finer weave may be more protective (3,10). Several studies have examined filtration, but fewer have examined fit or water resistance. Surgical masks are normally rated for fluid resistance, and cloth masks should be too. Masks should be able to prevent a stream of fluid flowing at a pressure of up to 160 mm Hg from seeping through the mask and potentially into the mouth. Furthermore, the degree of fit affects effectiveness because air flows in the direction of least resistance; if gaps are present on the sides of the mask, air will flow through those gaps instead of through the mask.
Cloth masks can be made in large quantities in a short time. They can be reused after being decontaminated by various techniques, ideally washing in hot water with soap. Other methods or products include using bleach, isopropyl alcohol, or hydrogen peroxide; autoclaving or microwaving; and application of ultraviolet radiation or dry heat (16). Unlike disposable medical masks and respirators, the material of cloth masks is unlikely to degrade from standard decontamination procedures. However, hospitals will have the extra burden of cleaning and decontaminating used masks. If healthcare workers perform decontamination themselves, they may fail to wash masks frequently enough and may risk self-contamination (31).
The general public can use cloth masks to protect against infection spread in the community. In community settings, masks may be used in 2 ways. First, they may be used by sick persons to prevent spread of infection (source control), and most health organizations (including WHO and CDC) recommend such use. In fact, a recent CDC policy change with regard to community use of cloth masks (1) is also based on high risk for transmission from asymptomatic or presymptomatic persons (32). According to some studies, ≈25%–50% of persons with COVID-19 have mild cases or are asymptomatic and potentially can transmit infection to others. So in areas of high transmission, mask use as source control may prevent spread of infection from persons with asymptomatic, presymptomatic, or mild infections. If medical masks are prioritized for healthcare workers, the general public can use cloth masks as an alternative. Second, masks may be used by healthy persons to protect them from acquiring respiratory infections; some randomized controlled trials have shown masks to be efficacious in closed community settings, with and without the practice of hand hygiene (33). Moreover, in a widespread pandemic, differentiating asymptomatic from healthy persons in the community is very difficult, so at least in high-transmission areas, universal face mask use may be beneficial. The general public should be educated about mask use because cloth masks may give users a false sense of protection because of their limited protection against acquiring infection (16). Correctly putting on and taking off cloth masks improves protection (Table). Taking a mask off is a high-risk process (34) because pathogens may be present on the outer surface of the mask and may result in self-contamination during removal (31).
