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MSphere Oct 2020Guidelines from the CDC and the WHO recommend the wearing of face masks to prevent the spread of coronavirus (CoV) disease 2019 (COVID-19); however, the protective...
Guidelines from the CDC and the WHO recommend the wearing of face masks to prevent the spread of coronavirus (CoV) disease 2019 (COVID-19); however, the protective efficiency of such masks against airborne transmission of infectious severe acute respiratory syndrome CoV-2 (SARS-CoV-2) droplets/aerosols is unknown. Here, we developed an airborne transmission simulator of infectious SARS-CoV-2-containing droplets/aerosols produced by human respiration and coughs and assessed the transmissibility of the infectious droplets/aerosols and the ability of various types of face masks to block the transmission. We found that cotton masks, surgical masks, and N95 masks all have a protective effect with respect to the transmission of infective droplets/aerosols of SARS-CoV-2 and that the protective efficiency was higher when masks were worn by a virus spreader. Importantly, medical masks (surgical masks and even N95 masks) were not able to completely block the transmission of virus droplets/aerosols even when completely sealed. Our data will help medical workers understand the proper use and performance of masks and determine whether they need additional equipment to protect themselves from infected patients. Airborne simulation experiments showed that cotton masks, surgical masks, and N95 masks provide some protection from the transmission of infective SARS-CoV-2 droplets/aerosols; however, medical masks (surgical masks and even N95 masks) could not completely block the transmission of virus droplets/aerosols even when sealed.
Topics: Aerosols; Air Microbiology; Betacoronavirus; COVID-19; Coronavirus Infections; Health Personnel; Humans; Masks; Pandemics; Pneumonia, Viral; SARS-CoV-2
PubMed: 33087517
DOI: 10.1128/mSphere.00637-20 -
Epidemiology and Infection Nov 2023We examined the association between face masks and risk of infection with SARS-CoV-2 using cross-sectional data from 3,209 participants in a randomized trial exploring...
We examined the association between face masks and risk of infection with SARS-CoV-2 using cross-sectional data from 3,209 participants in a randomized trial exploring the effectiveness of glasses in reducing the risk of SARS-CoV-2 infection. Face mask use was based on participants' response to the end-of-follow-up survey. We found that the incidence of self-reported COVID-19 was 33% (aRR 1.33; 95% CI 1.03-1.72) higher in those wearing face masks often or sometimes, and 40% (aRR 1.40; 95% CI 1.08-1.82) higher in those wearing face masks almost always or always, compared to participants who reported wearing face masks never or almost never. We believe the observed increase in the incidence of infection associated with wearing a face mask is likely due to unobservable and hence nonadjustable differences between those wearing and not wearing a mask. Observational studies reporting on the relationship between face mask use and risk of respiratory infections should be interpreted cautiously, and more randomized trials are needed.
Topics: Humans; COVID-19; SARS-CoV-2; Cross-Sectional Studies; Masks; Respiratory Tract Infections
PubMed: 37952983
DOI: 10.1017/S0950268823001826 -
Annali Di Igiene : Medicina Preventiva... 2021Health authorities and organizations consider non-medical face masks as an additional passive means to prevent virus diffusion. Communication strategies disseminate... (Review)
Review
BACKGROUND
Health authorities and organizations consider non-medical face masks as an additional passive means to prevent virus diffusion. Communication strategies disseminate information among the population that such masks are essential for mitigating virus diffusion. However, scientific studies are not conclusive in showing the undisputed filtration efficiency of fabric/cloth facial masks (both commercial and homemade).
OBJECTIVES
This study examines scientific data about the effectiveness of face masks before and during the COVID-19 emergency. Present trends in the making of commercial and homemade fabric/cloth face masks are also examined.
METHODS
Statistical data of published studies are analyzed and compared. Main considerations and sugge-stions are also extracted and discussed. Current approaches are examined for assessing the characteristics and effectiveness of fabric/cloth commercial and homemade face masks intended for the population.
RESULTS
Conflicting data exist as to whether non-medical masks have a protective effect from the spread of respiratory viruses. Both medical masks (MDs) and respiratory personal protection equipment (PPE) show a given effectiveness value.
CONCLUSION
Concerning commercial and homemade fabric/cloth masks, giving general indications on the choice of materials and their assemblage is difficult as it is not possible to assess the effectiveness of the filter media with respect to the kind of multiphase fluid that may be emitted upon breathing, sneezing, or coughing under different environmental conditions. This is particularly important because airflow rate, temperature, humidity, and duration of use will affect the performance of filter media. Moreover, while a mask may have excellent filter media, droplets may leak into the face-piece unless there is an adequate facial seal. In the presence of leaks, any type of mask may actually offer less protection independently of its nominal filtering effìciency.
Topics: Aerosols; Air Microbiology; COVID-19; Cough; Equipment Design; Evaluation Studies as Topic; Filtration; Humans; Humidity; Masks; Polypropylenes; Respiration; SARS-CoV-2; Sneezing; Temperature; Textiles
PubMed: 33258868
DOI: 10.7416/ai.2020.2390 -
Best Practice & Research. Clinical... Mar 2021We discuss the evidence behind mask use, including evidence for homemade masks, social distancing, and the local coronavirus disease-2019 (COVID-19) epidemics in... (Review)
Review
We discuss the evidence behind mask use, including evidence for homemade masks, social distancing, and the local coronavirus disease-2019 (COVID-19) epidemics in countries that initially employed more limited public health interventions. Given the absence of data for specific interventions in the rheumatic disease population, we reviewed the evidence available for the general population. The risk of poor outcomes with COVID-19 in patients with rheumatic diseases is a potential concern given the immunosuppression associated with these conditions and disease-modifying anti-rheumatic drug therapy, as well as advancing age and many of the comorbidities present in such patients. Infection prevention is key, for both individual patients and their community. Given the data collected from the general population, we recommend ongoing proper mask use, social distancing, and hand hygiene for patients with rheumatic diseases and encourage providers to counsel these patients in prevention strategies and attempt to dispel abundant misinformation.
Topics: COVID-19; Humans; Masks; Pandemics; Rheumatology; SARS-CoV-2
PubMed: 33536145
DOI: 10.1016/j.berh.2021.101663 -
Social Science & Medicine (1982) Oct 2022During the pre-vaccine period, the success of containing the spread of COVID-19 depends upon how communities respond to non-pharmaceutical mitigation policies such as...
During the pre-vaccine period, the success of containing the spread of COVID-19 depends upon how communities respond to non-pharmaceutical mitigation policies such as social distancing, wearing of masks, retail and dining constraints, crowd limitation, and shelter-in-place orders. Of these policies, shelter-in-place and social distancing are of central importance. By using county-level mobility data as a measure of a community's voluntary compliance with social distancing policies, this study found that counties who received strong state social distancing policy directives and who had a high pro-social character showed lower mobility on retail and recreation mobility and grocery and pharmacy mobility (better social distancing) after states reopened from shelter-in-place orders. Counties that experienced a longer duration of shelter-in-place orders showed higher mobility (less social distancing), implying that the duration of the shelter-in-place order deteriorated social distancing response after reopening. This may be because reopening sent a "safe" signal to these counties or resulted in a response to the pent-up demand inducing higher mobility. The results indicate that implementing shelter-in-place and social distancing policies to slow down the transmission of COVID-19 were not necessarily effective in motivating a county to reduce mobility voluntarily. A county's pro-social character and the duration of shelter-in-place order should be considered when designing COVID-19 mitigation policies.
Topics: COVID-19; Humans; Masks; Physical Distancing; United States
PubMed: 36041237
DOI: 10.1016/j.socscimed.2022.115308 -
American Journal of Public Health Jun 2022
Topics: Female; Gender Identity; Humans; Male; Masks; Sexual Behavior; Sexual and Gender Minorities; Surveys and Questionnaires
PubMed: 35420896
DOI: 10.2105/AJPH.2022.306834 -
PeerJ 2023Surgical masks remain a focal part of the CDC guidelines to decrease COVID-19 transmission. Evidence refuting significant effects of masking on ventilation is mostly... (Clinical Trial)
Clinical Trial
BACKGROUND
Surgical masks remain a focal part of the CDC guidelines to decrease COVID-19 transmission. Evidence refuting significant effects of masking on ventilation is mostly limited to small studies, with a paucity of studies on children, and none comparing children to adults.
METHODS
A total of 119 subjects were enrolled (71 adults, 49 children) in a prospective interventional study with each subject serving as their own mask-free control. End tidal CO2 (ETCO2), inspired CO2 (ICO2), and respiratory rate were measured by nasal cannula attached to an anesthesia machine D-fend module. Pulse oximetry and heart rate were also followed. After the mask-free period, an ASTM Level 3 disposable surgical mask was donned and 15 min of mask-worn data were collected.
RESULTS
A steady state was confirmed for ETCO2 and ICO2 over the masked period, and mean ICO2 levels rose significantly ( < 0.001) after masking in all age groups. The increase in ICO2 for the 2- to 7-year-old group of 4.11 mmHg (3.23-4.99), was significantly higher ( < 0.001) than the final ΔICO2 levels for both the 7- to 14-year-old group, 2.45 mmHg (1.79-3.12), and adults, 1.47 mmHg (1.18-1.76). For the pediatric group there was a negative, significant correlation between age and ΔICO2, r = -0.49, < 0.001. Masking resulted in a statistically significant ( < 0.01) rise in ETCO2 levels of 1.30 mmHg in adults and 1.36 mmHg in children. The final respective ETCO2 levels, 34.35 (33.55-35.15) and 35.07 (34.13-36.01), remained within normal limits. Pulse oximetry, heart rate, and respiratory rate were not significantly affected.
DISCUSSION
The physiology of mechanical dead space is discussed, including the inverse relationship of subject age ICO2. The methodology and results are compared to previously published studies which detracted from the physiologic safety of surgical masking.
CONCLUSIONS
The wearing of a surgical mask results in a statistically significant rise in ICO2 and a smaller rise in ETCO2. Because ETCO2 and other variables remain well within normal limits, these changes are clinically insignificant.
Topics: Humans; Child; Adult; Child, Preschool; Adolescent; Carbon Dioxide; Masks; Prospective Studies; COVID-19; Respiration
PubMed: 37342359
DOI: 10.7717/peerj.15474 -
Frontiers in Public Health 2021In the face of the novel virus SARS-CoV-2, scientists and the public are eager for evidence about what measures are effective at slowing its spread and preventing... (Review)
Review
In the face of the novel virus SARS-CoV-2, scientists and the public are eager for evidence about what measures are effective at slowing its spread and preventing morbidity and mortality. Other than mathematical modeling, studies thus far evaluating public health and behavioral interventions at scale have largely been observational and ecologic, focusing on aggregate summaries. Conclusions from these studies are susceptible to bias from threats to validity such as unmeasured confounding, concurrent policy changes, and trends over time. We offer recommendations on how to strengthen frequently applied study designs which have been used to understand the impact of interventions to reduce the spread of COVID-19, and suggest implementation-focused, pragmatic designs that, moving forward, could be used to build a robust evidence base for public health practice. We conducted a literature search of studies that evaluated the effectiveness of non-pharmaceutical interventions and policies to reduce spread, morbidity, and mortality of COVID-19. Our targeted review of the literature aimed to explore strengths and weaknesses of implemented studies, provide recommendations for improvement, and explore alternative real-world study design methods to enhance evidence-based decision-making. Study designs such as pre/post, interrupted time series, and difference-in-differences have been used to evaluate policy effects at the state or country level of a range of interventions, such as shelter-in-place, face mask mandates, and school closures. Key challenges with these designs include the difficulty of disentangling the effects of contemporaneous changes in policy and correctly modeling infectious disease dynamics. Pragmatic study designs such as the SMART (Sequential, Multiple-Assignment Randomized Trial), stepped wedge, and preference designs could be used to evaluate community re-openings such as schools, and other policy changes. As the epidemic progresses, we need to move from analyses of available data (appropriate for the beginning of the pandemic) to proactive evaluation to ensure the most rigorous approaches possible to evaluate the impact of COVID-19 prevention interventions. Pragmatic study designs, while requiring initial planning and community buy-in, could offer more robust evidence on what is effective and for whom to combat the global pandemic we face and future policy decisions.
Topics: COVID-19; Humans; Masks; Pandemics; SARS-CoV-2; Schools
PubMed: 34386470
DOI: 10.3389/fpubh.2021.657976 -
Annals of Internal Medicine Jun 2023Optimal use of masks for preventing COVID-19 is unclear. (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Optimal use of masks for preventing COVID-19 is unclear.
PURPOSE
To update an evidence synthesis on N95, surgical, and cloth mask effectiveness in community and health care settings for preventing SARS-CoV-2 infection.
DATA SOURCES
MEDLINE, EMBASE, medRxiv (3 June 2022 to 2 January 2023), and reference lists.
STUDY SELECTION
Randomized trials of interventions to increase mask use and risk for SARS-CoV-2 infection and observational studies of mask use that controlled for potential confounders.
DATA EXTRACTION
Two investigators sequentially abstracted study data and rated quality.
DATA SYNTHESIS
Three randomized trials and 21 observational studies were included. In community settings, mask use may be associated with a small reduced risk for SARS-CoV-2 infection versus no mask use, on the basis of 2 randomized trials and 7 observational studies. In routine patient care settings, surgical masks and N95 respirators may be associated with similar risk for SARS-CoV-2 infection, on the basis of 1 new randomized trial with some imprecision and 4 observational studies. Evidence from observational studies was insufficient to evaluate other mask comparisons due to methodological limitations and inconsistency.
LIMITATION
Few randomized trials, studies had methodological limitations and some imprecision, suboptimal adherence and pragmatic aspects of randomized trials potentially attenuated benefits, very limited evidence on harms, uncertain applicability to Omicron variant predominant era, meta-analysis not done due to heterogeneity, unable to formally assess for publication bias, and restricted to English-language articles.
CONCLUSION
Updated evidence suggests that masks may be associated with a small reduction in risk for SARS-CoV-2 infection in community settings. Surgical masks and N95 respirators may be associated with similar infection risk in routine patient care settings, but a beneficial effect of N95 respirators cannot be ruled out.
PRIMARY FUNDING SOURCE
None.
Topics: Humans; SARS-CoV-2; COVID-19; Masks; Delivery of Health Care
PubMed: 37186920
DOI: 10.7326/M23-0570 -
Enfermedades Infecciosas Y... Nov 2021The global health emergency caused by the current COVID-19 pandemic is resulting in a huge challenge at all levels. The use of masks may reduce the spread of the... (Review)
Review
INTRODUCTION
The global health emergency caused by the current COVID-19 pandemic is resulting in a huge challenge at all levels. The use of masks may reduce the spread of the infection by minimising the excretion of Flügge droplets. The objective of this study was to compile the evidence available on the use of masks in relation to respiratory infections.
METHODOLOGY
An umbrella review (review of systematic reviews) was conducted. Two reviewers independently carried out the screening process, data extraction and data analysis. Discrepancies were resolved with a third reviewer, and the assessment of the risk of bias of the studies was carried out using the AMSTAR 2 tool. The Rayyan QCRI program was used for the screening process.
RESULTS
A total of eight systematic reviews were included. The studies analysed the use of masks in the general population, in long-term care facilities, in hospitals and at mass gatherings, and compared the effectiveness thereof in preventing infection. The results of this review revealed that the use of masks is associated with a protective effect against respiratory infections in healthcare facilities, in long-term care facilities and at mass gatherings.
CONCLUSIONS
In light of the results, it seems reasonable to recommend the use of masks to the general population, but this use should be accompanied by a training programme to improve compliance, as not using them properly may increase the risk of infection.
Topics: COVID-19; Humans; Masks; Pandemics; Respiratory Tract Infections; SARS-CoV-2; Systematic Reviews as Topic
PubMed: 34446392
DOI: 10.1016/j.eimce.2021.08.002