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Objective The aim of this study was to compare the efficacy of cloth masks to medical masks in hospital healthcare workers (HCWs). The null hypothesis is that there is no difference between medical masks and cloth masks. Setting 14 secondary-level/tertiary-level hospitals in Hanoi, Vietnam. Participants 1607 hospital HCWs aged ≥18 years working full-time in selected high-risk wards. Intervention Hospital wards were randomised to: medical masks, cloth masks or a control group (usual practice, which included mask wearing). Participants used the mask on every shift for 4 consecutive weeks. Main outcome measure Clinical respiratory illness (CRI), influenza-like illness (ILI) and laboratory-confirmed respiratory virus infection. Results The rates of all infection outcomes were highest in the cloth mask arm, with the rate of ILI statistically significantly higher in the cloth mask arm (relative risk (RR)=13.00, 95% CI 1.69 to 100.07) compared with the medical mask arm. Cloth masks also had significantly higher rates of ILI compared with the control arm. An analysis by mask use showed ILI (RR=6.64, 95% CI 1.45 to 28.65) and laboratory-confirmed virus (RR=1.72, 95% CI 1.01 to 2.94) were significantly higher in the cloth masks group compared with the medical masks group. Penetration of cloth masks by particles was almost 97% and medical masks 44%. Conclusions This study is the first RCT of cloth masks, and the results caution against the use of cloth masks. This is an important finding to inform occupational health and safety. Moisture retention, reuse of cloth masks and poor filtration may result in increased risk of infection. Further research is needed to inform the widespread use of cloth masks globally. However, as a precautionary measure, cloth masks should not be recommended for HCWs, particularly in high-risk situations, and guidelines need to be updated. Trial registration number Australian New Zealand Clinical Trials Registry: ACTRN12610000887077.

Unprecedented demand for N95 respirators during the coronavirus disease 2019 (COVID-19) pandemic has led to a global shortage of these masks. We validated a rapidly applicable, low-cost decontamination protocol in compliance with regulatory standards to enable the safe reuse of N95 respirators. We inoculated 4 common models of N95 respirators with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and evaluated viral inactivation after disinfection for 60 minutes at 70°C and 0% relative humidity. Similarly, we evaluated thermal disinfection at 0% to 70% relative humidity for masks inoculated with Escherichia coli. We assessed masks subjected to multiple cycles of thermal disinfection for structural integrity using scanning electron microscopy and for protective functions using standards of the United States National Institute for Occupational Safety and Health for particle filtration efficiency, breathing resistance and respirator fit. A single heat treatment rendered SARS-CoV-2 undetectable in all mask samples. Compared with untreated inoculated control masks, E. coli cultures at 24 hours were virtually undetectable from masks treated at 70°C and 50% relative humidity (optical density at 600nm wavelength, 0.02±0.02 v. 2.77 ± 0.09, p < 0.001), but contamination persisted for masks treated at lower relative humidity. After 10 disinfection cycles, masks maintained fibre diameters similar to untreated masks and continued to meet standards for fit, filtration efficiency and breathing resistance. Thermal disinfection successfully decontaminated N95 respirators without impairing structural integrity or function. This process could be used in hospitals and long-term care facilities with commonly available equipment to mitigate the depletion of N95 masks.

RationaleMedical masks are commonly used by sick individuals with influenza-like illness (ILI) to prevent spread of infections to others, but clinical efficacy data are absent.ObjectiveDetermine whether medical mask use by sick individuals with ILI protects well contacts from related respiratory infections.Setting6 major hospitals in 2 districts of Beijing, China.DesignCluster randomised controlled trial.Participants245 index cases with ILI.InterventionIndex cases with ILI were randomly allocated to medical mask (n=123) and control arms (n=122). Since 43 index cases in the control arm also used a mask during the study period, an as-treated post hoc analysis was performed by comparing outcomes among household members of index cases who used a mask (mask group) with household members of index cases who did not use a mask (no-mask group).Main outcome measurePrimary outcomes measured in household members were clinical respiratory illness, ILI and laboratory-confirmed viral respiratory infection.ResultsIn an intention-to-treat analysis, rates of clinical respiratory illness (relative risk (RR) 0.61, 95% CI 0.18 to 2.13), ILI (RR 0.32, 95% CI 0.03 to 3.13) and laboratory-confirmed viral infections (RR 0.97, 95% CI 0.06 to 15.54) were consistently lower in the mask arm compared with control, although not statistically significant. A post hoc comparison between the mask versus no-mask groups showed a protective effect against clinical respiratory illness, but not against ILI and laboratory-confirmed viral respiratory infections.ConclusionsThe study indicates a potential benefit of medical masks for source control, but is limited by small sample size and low secondary attack rates. Larger trials are needed to confirm efficacy of medical masks as source control.Trial registration numberACTRN12613000852752; Results.

To the Editor.-In February 2020, the facilities manager of our hospital was tasked with evaluating our morgue airflow for compliance with the Centers for Disease Control and Prevention (CDC) standards for coronavirus disease 2019 (COVID-19) autopsies.1 The morgue had been built in 2015 to incorporate negative airflow that is exhausted to the outside of the hospital at a rate of 6 room air-exchanges per hour. [...]our initial autopsies lacked brain tissue. Centers for Disease Control and Prevention Web site. https://www.cdc.gov/coronavirus/ 2019-ncov/hcp/guidance-postmortem-specimens. html.

To survey healthcare workers (HCW) on availability and use of personal protective equipment (PPE) caring for COVID-19 patients in the intensive care unit (ICU). A web-based survey distributed worldwide in April 2020. We received 2711 responses from 1797 (67%) physicians, 744 (27%) nurses, and 170 (6%) Allied HCW. For routine care, most (1557, 58%) reportedly used FFP2/N95 masks, waterproof long sleeve gowns (1623; 67%), and face shields/visors (1574; 62%). Powered Air-Purifying Respirators were used routinely and for intubation only by 184 (7%) and 254 (13%) respondents, respectively. Surgical masks were used for routine care by 289 (15%) and 47 (2%) for intubations. At least one piece of standard PPE was unavailable for 1402 (52%), and 817 (30%) reported reusing single-use PPE. PPE was worn for a median of 4 h (IQR 2, 5). Adverse effects of PPE were associated with longer shift durations and included heat (1266, 51%), thirst (1174, 47%), pressure areas (1088, 44%), headaches (696, 28%), Inability to use the bathroom (661, 27%) and extreme exhaustion (492, 20%). HCWs reported widespread shortages, frequent reuse of, and adverse effects related to PPE. Urgent action by healthcare administrators, policymakers, governments and industry is warranted. [Display omitted] •Wide variability in what PPE is available for ICU staff caring for COVID-19 patients.•More than half report at least one PPE item missing or out of stock.•Adverse effects of wearing PPE reported by 80% of health care workers.•Adverse effects related to duration of a shift wearing PPE without taking a break.

Background Respiratory protective devices are critical in protecting against infection in healthcare workers at high risk of novel 2019 coronavirus disease (COVID‐19); however, recommendations are conflicting and epidemiological data on their relative effectiveness against COVID‐19 are limited. Purpose To compare medical masks to N95 respirators in preventing laboratory‐confirmed viral infection and respiratory illness including coronavirus specifically in healthcare workers. Data Sources MEDLINE, Embase, and CENTRAL from January 1, 2014, to March 9, 2020. Update of published search conducted from January 1, 1990, to December 9, 2014. Study Selection Randomized controlled trials (RCTs) comparing the protective effect of medical masks to N95 respirators in healthcare workers. Data Extraction Reviewer pair independently screened, extracted data, and assessed risk of bias and the certainty of the evidence. Data Synthesis Four RCTs were meta‐analyzed adjusting for clustering. Compared with N95 respirators; the use of medical masks did not increase laboratory‐confirmed viral (including coronaviruses) respiratory infection (OR 1.06; 95% CI 0.90‐1.25; I2 = 0%; low certainty in the evidence) or clinical respiratory illness (OR 1.49; 95% CI: 0.98‐2.28; I2 = 78%; very low certainty in the evidence). Only one trial evaluated coronaviruses separately and found no difference between the two groups (P = .49). Limitations Indirectness and imprecision of available evidence. Conclusions Low certainty evidence suggests that medical masks and N95 respirators offer similar protection against viral respiratory infection including coronavirus in healthcare workers during non–aerosol‐generating care. Preservation of N95 respirators for high‐risk, aerosol‐generating procedures in this pandemic should be considered when in short supply.

During the coronavirus disease 2019 pandemic, whether endoscopy generates aerosols needs to be determined. In patients undergoing upper gastrointestinal endoscopy with an enclosure covering their heads, 0.3-10-μm aerosols were measured for 60 seconds before, during, and after endoscopy by an optical counter. Whether aerosols increased in the situation with and without endoscopy was examined. The analysis included 103 consecutive patients undergoing endoscopy and 90 control patients. Aerosols increased significantly during endoscopy compared with the control group. Body mass index and burping were significant factors related to increased aerosols during endoscopy. Upper gastrointestinal endoscopy was an aerosol-generating procedure.

Any strategy to cope with an influenza pandemic must be based on the knowledge and tools that are available at the time an epidemic may occur. In the near term, when we lack an adequate supply of vaccine and antiviral medication, strategies that rely on social distancing and physical barriers will be relatively more prominent as means to prevent spread of disease. The use of respirators and facemasks is one key part of a larger strategy to establish barriers and increase distance between infected and uninfected individuals. Respirators and facemasks may have a role in both clinical care and community settings. Reusability of Facemasks During an Influenza Pandemic: Facing the Flu answers a specific question about the role of respirators and facemasks to reduce the spread of flu: Can respirators and facemasks that are designed to be disposable be reused safely and effectively? The committee-assisted by outstanding staff-worked intensively to review the pertinent literature; consult with manufacturers, researchers, and medical specialists; and apply their expert judgment. This report offers findings and recommendations based on the evidence, pointing to actions that are appropriate now and to lines of research that can better inform future decisions.

To characterize associations between exposures within and outside the medical workplace with healthcare personnel (HCP) SARS-CoV-2 infection, including the effect of various forms of respiratory protection. Case-control study. We collected data from international participants via an online survey. In total, 1,130 HCP (244 cases with laboratory-confirmed COVID-19, and 886 controls healthy throughout the pandemic) from 67 countries not meeting prespecified exclusion (ie, healthy but not working, missing workplace exposure data, COVID symptoms without lab confirmation) were included in this study. Respondents were queried regarding workplace exposures, respiratory protection, and extra-occupational activities. Odds ratios for HCP infection were calculated using multivariable logistic regression and sensitivity analyses controlling for confounders and known biases. HCP infection was associated with non-aerosol-generating contact with COVID-19 patients (adjusted OR, 1.4; 95% CI, 1.04-1.9; P = .03) and extra-occupational exposures including gatherings of ≥10 people, patronizing restaurants or bars, and public transportation (adjusted OR range, 3.1-16.2). Respirator use during aerosol-generating procedures (AGPs) was associated with lower odds of HCP infection (adjusted OR, 0.4; 95% CI, 0.2-0.8, P = .005), as was exposure to intensive care and dedicated COVID units, negative pressure rooms, and personal protective equipment (PPE) observers (adjusted OR range, 0.4-0.7). COVID-19 transmission to HCP was associated with medical exposures currently considered lower-risk and multiple extra-occupational exposures, and exposures associated with proper use of appropriate PPE were protective. Closer scrutiny of infection control measures surrounding healthcare activities and medical settings considered lower risk, and continued awareness of the risks of public congregation, may reduce the incidence of HCP infection.

In the human population, social contacts are a key for transmission of bacteria and viruses. The use of face masks seems to be critical to prevent the transmission of SARS-CoV-2 for the period, in which therapeutic interventions are lacking. In this review, we describe the history of masks from the middle age to modern times.