Trends and Characteristics of Suicide-Related Behaviors Before and After the COVID-19 Epidemic in Tottori, Japan: A Retrospective Study.

Background: In Japan, the number of suicides has increased since the coronavirus disease (COVID-19) epidemic. However, only a few studies have examined the trends among individuals who attempted suicide. In this study, we examined the background characteristics and motives of individuals who attempted suicide and visited the emergency room because of suicide-related behavior before and after the spread of COVID-19. Methods: This single-center retrospective observational study collected information from electronic medical records. We included patients who presented to the emergency department of Tottori University Hospital with suicide-related behaviors between May 1, 2017, to August 31, 2022. The period from May 1, 2017, through December 31, 2019, was designated as 'the period before COVID-19" (before-period), and that from January 1, 2020, through August 31, 2022, was designated as "the period after COVID-19" (after-period). We compared the total number of cases, their background, and motives for suicide-related behaviors between the before- and after-periods. Results: The total number of suicide events was 304. Of these, 182 and 122 occurred during the before-period and after-period, respectively. The incidence of the F3 category of the International Classification of Diseases, 10th Revision, increased, while that of the F4 and F6 categories decreased during the after-period. The proportion of suicide attempts due to health problems decreased and that of work problems increased during the after-period. Conclusion: The total number of suicide-related behaviors decreased after the COVID-19 pandemic. This may be because patients with psychiatric disorders other than depression and schizophrenia often engage in suicidal behavior through non-fatal methods, such as drug overdose and wrist-cutting, which may have led them to refrain from seeing a doctor. The proportion of suicidal motivation due to work-related fatigue has increased, perhaps because the quality and quantity of work changed significantly due to COVID-19.

Actual conditions of person-to-object contact and a proposal for prevention measures during the COVID-19 pandemic.

This study focused on human contact behavior with objects and discussed countermeasures during the COVID-19 pandemic across 15 location types. Reducing contact with objects and disinfecting items can be implemented at a relatively low cost. We created a protocol for organizing the objects, and 1260 subjects who went outside during a day between December 3-7, 2020 in Tokyo and Kanagawa, Japan were surveyed. The participants touched 7317 objects in total; the most common objects were doors, chairs, baskets, elevator equipment, and cash. One-way analysis of variance and Scheffé's multiple comparison test showed that supermarkets had the lowest mean and median values despite having the highest number of users, contact objects, and object types. Conversely, the values for hotels were the highest, significantly higher than that for other places, excluding amusement parks, workplaces, and schools and universities. Furthermore, the long-tailed frequency distribution of the number of objects suggests that the objects touched by many individuals are limited; thus, it is important to determine the objects to be prioritized for disinfection at each location. The data and protocol could inform infection countermeasures that properly address the contact realities as they pertain to people's behavior and objects.

Net-TF-SW: Event Popularity Quantification with Network Structure.

Event popularity quantification is essential in the determination of current trends in events on social media and the internet. Particularly, it is important during a crisis to ensure appropriate information transmission and prevention of false-rumor diffusion. Here, we propose Net-TF-SW - a noise-robust and explainable topic popularity analysis method. This method is applied to tweets related to COVID-19 and the Fukushima Daiichi Nuclear Disaster, which are two significant crises that have caused significant anxiety and confusion among Japanese citizens. The proposed method is compared to existing methods, and it is verified to be more robust with respect to noise.