Yasutaka Tetsuo, Murakami Michio, Iwasaki Yuichi, Naito Wataru, Onishi Masaki, Fujita Tsukasa, Imoto Seiya
Institute for Geo-Resources and Environment, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1, Higashi, Tsukuba, Ibaraki 305-8567, Japan.
Department of Health Risk Communication, Fukushima Medical University School of Medicine, 1 Hikarigaoka, Fukushima, Fukushima 960-1295, Japan.
Microb Risk Anal. 2022 Aug;21:100215. doi: 10.1016/j.mran.2022.100215. Epub 2022 Mar 31.
There is a need to evaluate and minimize the risk of novel coronavirus infections at mass gathering events, such as sports. In particular, to consider how to hold mass gathering events, it is important to clarify how the local infection prevalence, the number of spectators, the capacity proportion, and the implementation of preventions affect the infection risk. In this study, we used an environmental exposure model to analyze the relationship between infection risk and infection prevalence, the number of spectators, and the capacity proportion at mass gathering events in football and baseball games. In addition to assessing risk reduction through the implementation of various preventive measures, we assessed how face-mask-wearing proportion affects infection risk. Furthermore, the model was applied to estimate the number of infectors who entered the stadium and the number of newly infected individuals, and to compare them with actual reported cases. The model analysis revealed an 86-95% reduction in the infection risk due to the implementation of face-mask wearing and hand washing. Under conditions in which vaccine effectiveness was 20% and 80%, the risk reduction rates of infection among vaccinated spectators were 36% and 96%, respectively. Among the individual measures, face-mask wearing was particularly effective, and the infection risk increased as the face-mask-wearing proportion decreased. A linear relationship was observed between infection risk at mass gathering events and the infection prevalence. Furthermore, the number of newly infected individuals was also dependent on the number of spectators and the capacity proportion independent of the infection prevalence, confirming the importance of considering spectator capacity in infection risk management. These results highlight that it is beneficial for organisers to ensure prevention compliance and to mitigate or limit the number of spectators according to the prevalence of local infection. Both the estimated and reported numbers of newly infected individuals after the events were small, below 10 per 3-4 million spectators, despite a small gap between these numbers.
有必要在体育赛事等大型聚集活动中评估并尽量降低新型冠状病毒感染风险。特别是，为了考虑如何举办大型聚集活动，明确当地感染率、观众数量、容量比例以及预防措施的实施如何影响感染风险非常重要。在本研究中，我们使用环境暴露模型来分析足球和棒球比赛等大型聚集活动中感染风险与感染率、观众数量以及容量比例之间的关系。除了评估通过实施各种预防措施降低风险的情况外，我们还评估了戴口罩比例如何影响感染风险。此外，该模型还用于估计进入体育场的感染者数量和新感染个体数量，并将其与实际报告病例进行比较。模型分析显示，由于戴口罩和洗手措施的实施，感染风险降低了86% - 95%。在疫苗有效性为20%和80%的情况下，接种疫苗观众的感染风险降低率分别为36%和96%。在各项单独措施中，戴口罩尤为有效，且感染风险随着戴口罩比例的降低而增加。在大型聚集活动中观察到感染风险与感染率之间存在线性关系。此外，新感染个体数量还取决于观众数量和容量比例，与感染率无关，这证实了在感染风险管理中考虑观众容量的重要性。这些结果凸显出，对于组织者来说，确保预防措施的合规性以及根据当地感染率减轻或限制观众数量是有益的。尽管活动后估计的和报告的新感染个体数量之间存在小差距，但两者数量都很少，每300 - 400万观众中低于10例。
