COVID-19 infection risk assessment and management at the Tokyo 2020 Olympic and Paralympic Games: A scoping review.

The Tokyo 2020 Olympic and Paralympic Games was one of the largest international mass-gathering events held after the beginning of coronavirus disease 2019 (COVID-19) pandemic. In this scoping review, we extracted papers discussing COVID-19 risk assessment or management at the Tokyo 2020 Games to determine the nature of studies that were conducted. Among the 75 papers obtained from two search engines (PubMed and ScienceDirect) and four papers collected from hand-searches, 30 papers were extracted. Only eight papers performed both COVID-19 prior risk assessment and quantitative evaluation of effectiveness measures, highlighting the importance of rapid, solution-focused risk assessment. Furthermore, this review revealed that the findings regarding the spread of COVID-19 infection to citizens in the host country were inconsistent depending on the assessment methods and that assessments of the spread of infection outside the host country were lacking.

COVID-19 infection risk assessment and management at the Tokyo 2020 Olympic and Paralympic Games: A scoping review

The Tokyo 2020 Olympic and Paralympic Games was one of the largest international mass-gathering events held after the beginning of coronavirus disease 2019 (COVID-19) pandemic. In this scoping review, we extracted papers discussing COVID-19 risk assessment or management at the Tokyo 2020 Games to determine the nature of studies that were conducted. Among the 75 papers obtained from two search engines (PubMed and ScienceDirect) and four papers collected from hand-searches, 30 papers were extracted. Only eight papers performed both COVID-19 prior risk assessment and quantitative evaluation of effectiveness measures, highlighting the importance of rapid, solution-focused risk assessment. Furthermore, this review revealed that the findings regarding the spread of COVID-19 infection to citizens in the host country were inconsistent depending on the assessment methods and that assessments of the spread of infection outside the host country were lacking.

Interventions to prevent surface transmission of an infectious virus based on real human touch behavior: a case study of the norovirus.

OBJECTIVES: Infectious viruses (e.g., SARS-CoV-2, norovirus) can transmit through surfaces. Norovirus has infected millions of individuals annually. Interventions on norovirus transmission in high-risk indoor environment are important. METHODS: This study focused on a restaurant in Guangzhou, China. More than 41,000 touches by both diners and staff members were collected using video cameras. A surface transmission model was developed and combined with these real human touch behaviors to analyze the effectiveness of different norovirus prevention strategies. RESULTS: When the virus carrier was a diner, the virus intake fraction of diners in the same table was the highest. Increasing the touch frequency on personal private surfaces would reduce the virus exposure. The virus intake fraction was reduced by 18.4% on average if public surfaces were not touched. Optimization on surface materials could reduce the virus intake fraction by 86.6%. Additionally, disinfecting tablecloths, clothes of diners, and chairs were the three most effective surface disinfection strategies. CONCLUSION: Controlling human touch behavior (e.g., reducing the self-touches on mucous membranes) is more effective than surface disinfection in controlling norovirus transmission, but surface disinfection cannot be ignored because human behavior is difficult to be controlled.

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

The 2020 Olympic/Paralympic Games have been postponed to 2021, due to the COVID-19 pandemic. We developed a model that integrated source-environment-receptor pathways to evaluate how preventive efforts can reduce the infection risk among spectators at the opening ceremony of Tokyo Olympic Games. We simulated viral loads of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emitted from infectors through talking/coughing/sneezing and modeled temporal environmental behaviors, including virus inactivation and transfer. We performed Monte Carlo simulations to estimate the expected number of newly infected individuals with and without preventive measures, yielding the crude probability of a spectator being an infector among the 60,000 people expected to attend the opening ceremony. Two indicators, i.e., the expected number of newly infected individuals and the newly infected individuals per infector entry, were proposed to demonstrate the extent of achievable infection risk reduction levels by implementing possible preventive measures. A no-prevention scenario produced 1.5-1.7 newly infected individuals per infector entry, whereas a combination of cooperative preventive measures by organizers and the spectators achieved a 99% risk reduction, corresponding to 0.009-0.012 newly infected individuals per infector entry. The expected number of newly infected individuals was calculated as 0.005 for the combination of cooperative preventive scenarios with the crude probability of a spectator being an infector of 1 × 10-5. Based on our estimates, a combination of cooperative preventions between organizers and spectators is required to prevent a viral spread at the Tokyo Olympic/Paralympic Games. Further, under the assumption that society accepts < 10 newly infected persons traced to events held during the entire Olympic/Paralympic Games, we propose a crude probability of infectors of < 5 × 10-5 as a benchmark for the suppression of the infection. This is the first study to develop a model that can assess the infection risk among spectators due to exposure pathways at a mass gathering event.

Regulatory Science on Novel Coronavirus Disease ** *** **** *****

At the 2020 annual meeting of The Society of Risk Analysis Japan, we hosted a special session focusing on novel coronavirus disease (COVID-19) as an emerging risk. In the context of the COVID-19 pandemic, the regulatory science perspective is very important as countermeasures have to be decided in a very limited time and without sufficient scientific knowledge. The objective of the session was to discuss the contribution of risk science to countermeasures against COVID-19. The topics were as follows: (1) science and policy under the risk governance;(2) risk assessment at mass gathering events;(3) regulatory science of the infection risk management and the regulatory framework issue;(4) comparison of mortality risk and economic impact.

A Systematic Review of the Potential Disinfectants against Coronavirus toward Risk Mitigation Strategies for COVID-19 Contact Infection Route

Coronavirus disease 2019 (COVID-19) is an emerging social risk with a rapid increase in cases of 5,200,000 and deaths of 330,000 (23/May/2020) since its first identification in Wuhan China, in December 2019. The COVID-19 is spreading all over the world as an emerging pandemic, and global society need fundamental risk management concepts against SARS-CoV-2 infection. Human-to-human transmissions have been facilitating via droplets and contaminated surfaces to hands. Therefore, we developed the systematic review comprehensively using available information about coronaviruses on environmental surfaces and inactivation mechanisms of antiviral chemicals possible to apply as chemical disinfectants. The analysis of literatures revealed that SARS-CoV-2 can persist on environmental surfaces like plastics and glasses for up to 7 days, but might be efficiently inactivated with 45-81% ethanol, 50-80% 2-propanol, 0.05-0.3% benzalkonium chloride, various detergents, 0.5% hydrogen peroxide or 0.045% sodium hypochlorite within 30 sec-10 min or 30 min. As no specific therapies are available for SARS-CoV-2, we propose the risk mitigation on the contact infection route by anti-virus household products is promising for prevention of further spread via hands to mouth, nose, and eyes. and to control this novel social problem.