Face masks and COVID-19: don’t let perfect be the enemy of good

Cowling, Benjamin J.; Leung, Gabriel M.

doi:10.2807/1560-7917.es.2020.25.49.2001998

Cited by 16 publications

(12 citation statements)

References 39 publications

(40 reference statements)

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“…Mask interventions were also implemented unevenly (as advisories or mandates) and usually only in limited settings. Our separate evidence review [42] found that mask wearing to stop respiratory disease transmission is likely to be only modestly effective, but we agree that when it comes to a pandemic situation, small protective measures may have cumulative important benefits [43]. We relied on published and observed data which may have suffered from problems of under-ascertainment; the true effect of specific interventions may depend on true community prevalence that was not measured accurately enough.…”

Section: Discussionmentioning

confidence: 99%

Impact of non-pharmaceutical interventions against COVID-19 in Europe in 2020: a quasi-experimental non-equivalent group and time series design study

et al. 2021

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Introduction The current pandemic of coronavirus disease (COVID-19) is unparalleled in recent history as are the social distancing interventions that have led to a considerable halt on the economic and social life of so many countries. Aim We aimed to generate empirical evidence about which social distancing measures had the most impact in reducing case counts and mortality. Methods We report a quasi-experimental (observational) study of the impact of various interventions for control of the outbreak through 24 April 2020. Chronological data on case numbers and deaths were taken from the daily published figures by the European Centre for Disease Prevention and Control and dates of initiation of various control strategies from the Institute of Health Metrics and Evaluation website and published sources. Our complementary analyses were modelled in R using Bayesian generalised additive mixed models and in STATA using multilevel mixed-effects regression models. Results From both sets of modelling, we found that closure of education facilities, prohibiting mass gatherings and closure of some non-essential businesses were associated with reduced incidence whereas stay-at-home orders and closure of additional non-essential businesses was not associated with any independent additional impact. Conclusions Our findings are that schools and some non-essential businesses operating ‘as normal’ as well as allowing mass gatherings were incompatible with suppressing disease spread. Closure of all businesses and stay at home orders are less likely to be required to keep disease incidence low. Our results help identify what were the most effective non-pharmaceutical interventions in this period.

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Section: Discussionmentioning

confidence: 99%

Impact of non-pharmaceutical interventions against COVID-19 in Europe in 2020: a quasi-experimental non-equivalent group and time series design study

et al. 2021

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“…Our estimate of a relative susceptibility of 0.88 (CrI: 0.81-0.96) in vaccinated students, which translates into a vaccine effectiveness of 12% (CrI: 9-19%), is broadly consistent with this prior estimate. While existing evidence for the effectiveness of mask policies for the control of respiratory infections is still limited (44,45), our estimates of small protective effects acting on the relative susceptibility (0.77; CrI: 0.71-0.85) and infectiousness (0.65; CrI: 0.55-0.78) lie within a plausible range based on evidence available to date (44,(46)(47)(48). Increased susceptibility associated with hand washing in our analysis, however, does not align with existing findings (49,50).…”

Section: Discussionmentioning

confidence: 99%

Within and between classroom transmission patterns of seasonal influenza among primary school students in Matsumoto city, Japan

Endo

Uchida

Hayashi

et al. 2021

Preprint

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Schools play a central role in the transmission of many respiratory infections. Heterogeneous social contact patterns associated with the social structures of schools (i.e. classes/grades) are likely to influence the within-school transmission dynamics, but data-driven evidence on fine-scale transmission patterns between students has been limited. Using a mathematical model, we analysed a large-scale dataset of seasonal influenza outbreaks in Matsumoto city, Japan to infer social interactions within and between classes/grades from observed transmission patterns. While the relative contribution of within-class and within-grade transmissions to the reproduction number varied with the number of classes per grade, tThe overall within-school reproduction number, which determines the initial growth of cases and the risk of sustained transmission, was only minimally associated with class sizes and the number of classes per grade. This finding suggests that interventions that change the size and number of classes, e.g. splitting classes and staggered attendance, may have limited effect on the control of school outbreaks. We also found that vaccination and mask-wearing of students were associated with reduced susceptibility (vaccination and mask-wearing) and infectiousness (mask-wearing) and hand washing with increased susceptibility. Our results show how analysis of fine-grained transmission patterns between students can improve understanding of within-school disease dynamics and provide insights into the relative impact of different approaches to outbreak control.

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“…Since the beginning of the 2020 pandemic, there has been discussion on the efficacy of face coverings and masks. However, recent studies show clear benefits in reducing transmission [ 1 , 2 , 3 , 4 ], and the use of face coverings has been accepted by the wider scientific community. In one study, [ 5 ], two hairdressers both tested positive for COVID-19 and wore a double layer face mask while working.…”

Section: Introductionmentioning

confidence: 99%

Use of Multiple Low Cost Carbon Dioxide Sensors to Measure Exhaled Breath Distribution with Face Mask Type and Wearing Behaviour

Salman

Khan

Lim

et al. 2021

Sensors

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The use of cloth face coverings and face masks has become widespread in light of the COVID-19 pandemic. This paper presents a method of using low cost wirelessly connected carbon dioxide (CO2) sensors to measure the effects of properly and improperly worn face masks on the concentration distribution of exhaled breath around the face. Four types of face masks are used in two indoor environment scenarios. CO2 as a proxy for exhaled breath is being measured with the Sensirion SCD30 CO2 sensor, and data are being transferred wirelessly to a base station. The exhaled CO2 is measured in four directions at various distances from the head of the subject, and interpolated to create spatial heat maps of CO2 concentration. Statistical analysis using the Friedman’s analysis of variance (ANOVA) test is carried out to determine the validity of the null hypotheses (i.e., distribution of the CO2 is same) between different experiment conditions. Results suggest CO2 concentrations vary little with the type of mask used; however, improper use of the face mask results in statistically different CO2 spatial distribution of concentration. The use of low cost sensors with a visual interpolation tool could provide an effective method of demonstrating the importance of proper mask wearing to the public.

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Face masks and COVID-19: don’t let perfect be the enemy of good

Cited by 16 publications

References 39 publications

Impact of non-pharmaceutical interventions against COVID-19 in Europe in 2020: a quasi-experimental non-equivalent group and time series design study

Impact of non-pharmaceutical interventions against COVID-19 in Europe in 2020: a quasi-experimental non-equivalent group and time series design study

Within and between classroom transmission patterns of seasonal influenza among primary school students in Matsumoto city, Japan

Use of Multiple Low Cost Carbon Dioxide Sensors to Measure Exhaled Breath Distribution with Face Mask Type and Wearing Behaviour

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