COVID-19 risk assessment at the opening ceremony of the Tokyo 2020 Olympic Games

Murakami, Michio; Miura, Fuminari; Kitajima, Masaaki; Fujii, Kenkichi; Yasutaka, Tetsuo; Iwasaki, Yoshiaki; Ono, Kyoko; Shimazu, Yuzo; Sorano, Sumire; Okuda, Tomoaki; Ozaki, Akihiko; Katayama, Kotoe; Nishikawa, Yoshitaka; Kobashi, Yurie; Sawano, Toyoaki; Abe, Tomoki; Saito, Masaya; Tsubokura, Masaharu; Naito, Wataru; Imoto, Seiya

doi:10.1016/j.mran.2021.100162

Cited by 29 publications

(60 citation statements)

References 36 publications

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“…Similarly, sneezing increased the risk of infection to 3.66 × 10 −1 and 3.67 × 10 −1 for men and women, respectively. All the scenarios demonstrated higher risks than the 5 × 10 −5 benchmark value (Murakami, Miura, et al, 2021). We therefore showed that receptors had a high risk of infection when using an unventilated public toilet without wearing a protective mask.…”

Section: Resultsmentioning

confidence: 85%

“…The risk assessment was conducted by following the QMRA framework. Given the lack of dose-response information for SARS-CoV-2, the SARS-CoV data sets (Watanabe, Bartrand, et al, 2010) that had been utilized in various SARS-CoV-2 QMRA studies (Murakami, Miura, et al, 2021; Dada and Gyawali, 2021; Zaneti, Girardi, et al, 2021; Cortellessa, Stabile, et al, 2021) were applied. The risk of infection followed the exponential model (Eq.…”

Section: Methodsmentioning

confidence: 99%

“…It is becoming increasingly important to fully consider the uncertainties, including those in the 97.5th percentile, to maintain a sufficient safety margin for decision-making during the COVID-19 pandemic (Zhang, Ji, et al, 2021). The estimated risk was compared to a benchmark of 1 infection per 20,000 exposed people per event (5 × 10 −5 ) (Murakami, Miura, et al, 2021). A sensitivity analysis was also conducted to determine the effects of the input variables on the risk calculation.…”

Section: Methodsmentioning

confidence: 99%

“…Quantitative microbial risk assessment (QMRA) is a valuable tool used to quantitatively estimate human health risks associated with exposure to pathogens in different environmental matrices (Rose and Gerba, 1991; Haas, Rose, et al, 2014). The QMRA framework has been applied to estimate SARS-CoV-2 transmission risk to wastewater treatment plant workers (Dada and Gyawali, 2021; Zaneti, Girardi, et al, 2021), Tokyo 2020 Olympic Games attendees (Murakami, Miura, et al, 2021), and confined vehicle passengers and shared room users (Schijven, Vermeulen, et al, 2021). In the present study, we aimed to estimate the risk of infection associated with public toilet exposure to SARS-CoV-2 through airborne transmission using the QMRA approach.…”

Section: Introductionmentioning

confidence: 99%

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Effects of face masks and ventilation on the risk of SARS-CoV-2 respiratory transmission in public toilets: a quantitative microbial risk assessment

Denpetkul

Sittipunsakda

Pumkaew

et al. 2021

Preprint

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Public toilets could increase the risk of COVID-19 infection via airborne transmission; however, related research is limited. We aimed to estimate SARS-CoV-2 infection risk through respiratory transmission using a quantitative microbial risk assessment framework by retrieving SARS-CoV-2 concentrations from the swab tests of 251 Thai patients. Three virus-generating scenarios were investigated: an infector breathing, breathing with a cough, and breathing with a sneeze. Infection risk (97.5th percentile) was as high as 10−3 with breathing and increased to 10−1 with a cough or sneeze, thus all higher than the risk benchmark of 5 × 10−5 per event. No significant gender differences for toilet users (receptors) were noted. The highest risk scenario of breathing and a sneeze was further evaluated for risk mitigation measures. Risk mitigation to lower than the benchmark succeeded only when the infector and receptor simultaneously wore an N95 respirator or surgical mask and when the receptor wore an N95 respirator and the infector wore a denim fabric mask. Ventilation up to 20 air changes per hour (ACH), beyond the 12-ACH suggested by the WHO, did not mitigate risk. Virus concentration, volume of expelled droplets, and receptor dwell time were identified as the main contributors to transmission risk.Highlights-The use of public toilets poses a risk of SARS-CoV-2 respiratory transmission-Highest risks generated in the order of sneezing, coughing, and breathing-No gender differences in risk by counteracting dwell times and inhalation rates-Ventilation did not reduce risk even at 20 ACH, beyond the WHO-recommended value-N95 and surgical masks offer the most effective risk mitigation to toilet usersGraphical abstract

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Section: Resultsmentioning

confidence: 85%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effects of face masks and ventilation on the risk of SARS-CoV-2 respiratory transmission in public toilets: a quantitative microbial risk assessment

Denpetkul

Sittipunsakda

Pumkaew

et al. 2021

Preprint

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“…It has been estimated by quantitative microbial risk assessment that the implementation of measures according to the route of infection, such as physical distancing and wearing of face masks for droplet transmission, ventilation for airborne transmission and decontamination and hand washing for contact transmission, is useful for controlling the risk of infection at mass gathering events. 3 Therefore, it is important to comply with the implemented measures and to ensure the effective compliance of spectators, who must wear face masks and maintain physical distancing, as well as organizers, who are responsible for ventilation and decontamination of the venue.…”

mentioning

confidence: 99%

Living with COVID-19: mass gatherings and minimizing risk

Murakami

Yasutaka

Onishi

et al. 2021

QJM: An International Journal of Medicine

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During the COVID-19 pandemic, it has been important to both minimise the risk of infection and restore daily life. As a typical example, mass gathering events, such as sporting events, are gradually becoming more common, thanks to the measures taken to contain COVID-19. Some pilot studies have been launched at governments’ initiative to investigate the risk of infection without measures such as face masks and physical distancing at mass gathering events, but the ethics of these studies should be carefully considered. On the other hand, it is still beneficial to implement infection control measures at mass gathering events and, in parallel, to estimate the risk of infection with measures in place, especially under a lack of vaccination progress or the spread of mutant strains possibly resistant to vaccines. To help improve compliance with measures taken by spectators and organizers and to ensure their effectiveness, we have conducted quantitative evaluations of the implementation of such measures by monitoring CO2 concentrations, assessing the proportion of people wearing face masks and analysing human flow at the event. This approach allows us to share our observations with stakeholders and participants, enabling us to protect the culture of mass gathering events, minimise the risk of infection, and restore a sense of well-being in daily life.

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Contributions and problems of mathematical models in COVID‐19 prevention in Japan

Kakehashi,

Matsuda

2024

Population Ecology

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This article reviews the essential role of mathematical models in understanding and combatting the pandemic of novel coronaviruses, in particular focusing the advance in the use of mathematical models in disease control in Japan. Highlighting the integral role of mathematical models in public health, the article introduces a model that factors in the heterogeneity of infectious contacts, concentrating on the effectiveness of testing and isolation, alongside a model that involves economic losses. The models exhibit how, given such heterogeneity, milder behavioral restrictions can still achieve suppression, rigorous testing and isolation can effectively curb the spread, and containment measures can mitigate economic losses. These models aid in grasping the complicated dynamics of disease transmission and optimizing interventions. The knowledge of population ecology is also considered effective for public health in statistical analysis, organizing concepts using dynamic mathematical models, which lead to policy proposals and deepen understanding. Evolution theory may help the understanding of virulence subject to change. However, effective prevention necessitates not only models but also the practical implementation of efficacious measures. The cooperation of various disciplines is particularly crucial in achieving a balance between health measures, economic interests, and human rights. Moreover, the article acknowledges the limitations of models and underscores the significance of real‐world execution. Overall, the article advocates for a broader outlook to tackle future pandemics and related challenges, underscoring the importance of ongoing academic cooperation and global governance to effectively address emerging infectious diseases and their far‐reaching implications.

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COVID-19 risk assessment at the opening ceremony of the Tokyo 2020 Olympic Games

Cited by 29 publications

References 36 publications

Effects of face masks and ventilation on the risk of SARS-CoV-2 respiratory transmission in public toilets: a quantitative microbial risk assessment

Effects of face masks and ventilation on the risk of SARS-CoV-2 respiratory transmission in public toilets: a quantitative microbial risk assessment

Living with COVID-19: mass gatherings and minimizing risk

Contributions and problems of mathematical models in COVID‐19 prevention in Japan

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