Peculiar weather patterns effects on air pollution and COVID-19 spread in Tokyo metropolis.

As a pandemic hotspot in Japan, between March 1, 2020-October 1, 2022, Tokyo metropolis experienced seven COVID-19 waves. Motivated by the high rate of COVID-19 incidence and mortality during the seventh wave, and environmental/health challenges we conducted a time-series analysis to investigate the long-term interaction of air quality and climate variability with viral pandemic in Tokyo. Through daily time series geospatial and observational air pollution/climate data, and COVID-19 incidence and death cases, this study compared the environmental conditions during COVID-19 multiwaves. In spite of five State of Emergency (SOEs) restrictions associated with COVID-19 pandemic, during (2020-2022) period air quality recorded low improvements relative to (2015-2019) average annual values, namely: Aerosol Optical Depth increased by 9.13% in 2020 year, and declined by 6.64% in 2021, and 12.03% in 2022; particulate matter PM2.5 and PM10 decreased during 2020, 2021, and 2022 years by 10.22%, 62.26%, 0.39%, and respectively by 4.42%, 3.95%, 5.76%. For (2021-2022) period the average ratio of PM2.5/PM10 was (0.319 ± 0.1640), showing a higher contribution to aerosol loading of traffic-related coarse particles in comparison with fine particles. The highest rates of the daily recorded COVID-19 incidence and death cases in Tokyo during the seventh COVID-19 wave (1 July 2022-1 October 2022) may be attributed to accumulation near the ground of high levels of air pollutants and viral pathogens due to: 1) peculiar persistent atmospheric anticyclonic circulation with strong positive anomalies of geopotential height at 500 hPa; 2) lower levels of Planetary Boundary Layer (PBL) heights; 3) high daily maximum air temperature and land surface temperature due to the prolonged heat waves (HWs) in summer 2022; 4) no imposed restrictions. Such findings can guide public decision-makers to design proper strategies to curb pandemics under persistent stable anticyclonic weather conditions and summer HWs in large metropolitan areas.

Behavioral changes of preventive activities of influenza among children in satellite cities of a metropolitan area of Tokyo, Japan, by the COVID-19 pandemic.

OBJECTIVE: In children in a metropolitan area of Tokyo, Japan, behavioral change and influenza infection associated with the frequency of nonpharmaceutical interventions (NPI) was assessed from the 2018-2019 season (Preseason) and the 2020-2021 season (coronavirus disease 2019 [COVID-19] season). METHODS: We conducted an exclusive survey among children attending preschool, elementary school, and junior high school in the Toda and Warabi regions, Japan, during the 2018-2019 (Preseason, distributed via mail) and 2020-2021 seasons (COVID-19 season, conducted online). The proportion of preventive activities (hand washing, face mask-wearing, and vaccination) was compared in the Preseason with that of the COVID-19 season. The multivariate logistic regression model was further applied to calculate the adjusted odds ratio (AOR) with 95% confidence intervals (CIs) for influenza infection associated with NPI frequency (hand washing and face mask wearing) in each Preseason and COVID-19 season. RESULTS: The proportion of vaccinated children who carried out hand washing and face mask wearing was remarkably higher during the COVID-19 season (48.8%) than in the Preseason (18.2%). A significant influenza infection reduction was observed among children who washed hands and wore face masks simultaneously (AOR, 0.87; 95% CI, 0.76-0.99; P = 0.033). CONCLUSIONS: A strong interest and performance in the intensive measures for the prevention of influenza under the COVID-19 pandemic was demonstrated. Positive association was observed from a combination of NPI, hand washing, and face mask-wearing and influenza infection. This study's findings could help in activities or preventive measures against influenza and other communicable diseases in children.

Pediatric emergency healthcare utilization during the coronavirus disease 2019 pandemic in Tokyo.

BACKGROUND: Various public health interventions have been implemented against the coronavirus disease 2019 pandemic. We investigated changes in pediatric emergency healthcare utilization during the current pandemic. METHODS: Based on data on outpatient healthcare visits to one pediatric emergency department in Tokyo, Japan, the descriptive, cross-sectional study compared the number of emergency department visits in 2020 to the number in the previous 3 years. Data were extracted from the electronic triage reporting system. The primary outcome was the number of emergency department visits. The characteristics of patients by age group were also investigated. RESULTS: A 40.6% reduction in pediatric emergency healthcare utilization was observed during the study period, with the greatest decrease occurring in the number of visits for fever. However, while the number of patients with a complaint with an exogenous cause decreased, the proportion of these patients increased. Although social activities in the greater community have now almost normalized, and only a slight increase in the number of patients with fever has been reported, the number of emergency department visits remains lower than in previous years as of this writing. CONCLUSIONS: Public health interventions led to a reduction in emergency department visits, thereby allowing time to redistribute health-care resources.

Causes of death of forensic autopsy cases tested positive for COVID-19 in Tokyo Metropolis, Japan.

BACKGROUND: The profile of deaths related to coronavirus disease of 2019 (COVID-19) that occurred outside the hospital in Japan remains unclear because of cautious stance on performing autopsies of COVID-19 positive cases. METHODS: Autopsy cases that tested positive for COVID-19 in the Tokyo Metropolis from April 2020 to July 2022 were handled by medical examiners (n = 41). Age, sex, medical history, autopsy findings, cause of death, postmortem computed tomography (PMCT) findings, and the causal relationship between death and COVID-19 were examined. RESULTS: The mean age of the deceased was 58.0 years (range: 28-96 years), and the study sample consisted of 33 males (80.5%) and 8 females (19.5%). The most frequent medical histories were hypertension (n = 7) and diabetes (n = 7), followed by mental disorders (n = 5). Nineteen cases showed a body mass index ≧25.0 (46.3%). The leading cause of death was pneumonia (n = 17), in which diffuse ground-glass opacification and/or consolidation was noted on PMCT. There were 26 deaths directly related to COVID-19 (63.4%), including pneumonia, myocarditis, laryngotracheobronchitis, and emaciation. The proportion of deaths directly related to COVID-19 was lower after 2022 (42.1%) than prior to 2022 (81.8%). CONCLUSION: Pneumonia was the leading cause of death in this study sample; however, the causes of death in COVID-19 positive cases varied, especially after 2022, when the omicron variant was dominant. Mortality statistics may be affected by viral mutations, and the results of this study further emphasize the need for autopsy because more differential diagnoses should be considered in the phase of the omicron variant.

Transmission of COVID-19 in Nightlife, Household, and Health Care Settings in Tokyo, Japan, in 2020.

Importance: There have been few studies on the heterogeneous interconnection of COVID-19 outbreaks occurring in different social settings using robust, surveillance epidemiological data. Objectives: To describe the characteristics of COVID-19 transmission within different social settings and to evaluate settings associated with onward transmission to other settings. Design, Setting, and Participants: This is a case series study of laboratory-confirmed COVID-19 cases in Tokyo between January 23 and December 5, 2020, when vaccination was not yet implemented. Using epidemiological investigation data collected by public health centers, epidemiological links were identified and classified into 7 transmission settings: imported, nightlife, dining, workplace, household, health care, and other. Main Outcomes and Measures: The number of cases per setting and the likelihood of generating onward transmissions were compared between different transmission settings. Results: Of the 44 054 confirmed COVID-19 cases in this study, 25 241 (57.3%) were among male patients, and the median (IQR) age of patients was 36 (26-52) years. Transmission settings were identified in 13 122 cases, including 6768 household, 2733 health care, and 1174 nightlife cases. More than 6600 transmission settings were detected, and nightlife (72 of 380 [18.9%]; P < .001) and health care (119 [36.2%]; P < .001) settings were more likely to involve 5 or more cases than dining, workplace, household, and other settings. Nightlife cases appeared in the earlier phase of the epidemic, while household and health care cases appeared later. After adjustment for transmission setting, sex, age group, presence of symptoms, and wave, household and health care cases were less likely to generate onward transmission compared with nightlife cases (household: adjusted odds ratio, 0.03; 95% CI, 0.02-0.05; health care: adjusted odds ratio, 0.57; 95% CI, 0.41-0.79). Household settings were associated with intergenerational transmission, while nonhousehold settings mainly comprised transmission between the same age group. Among 30 932 cases without identified transmission settings, cases with a history of visiting nightlife establishments were more likely to generate onward transmission to nonhousehold settings (adjusted odds ratio, 5.30 [95% CI, 4.64-6.05]; P < .001) than those without such history. Conclusions and Relevance: In this case series study, COVID-19 cases identified in nightlife settings were associated with a higher likelihood of spreading COVID-19 than household and health care cases. Surveillance and interventions targeting nightlife settings should be prioritized to disrupt COVID-19 transmission, especially in the early stage of an epidemic.

Cumulative and undiagnosed SARS-CoV-2 infection among the staff of a medical research centre in Tokyo after the emergence of variants.

To describe the trend of cumulative incidence of coronavirus disease 19 (COVID-19) and undiagnosed cases over the pandemic through the emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants among healthcare workers in Tokyo, we analysed data of repeated serological surveys and in-house COVID-19 registry among the staff of National Center for Global Health and Medicine. Participants were asked to donate venous blood and complete a survey questionnaire about COVID-19 diagnosis and vaccine. Positive serology was defined as being positive on Roche or Abbott assay against SARS-CoV-2 nucleocapsid protein, and cumulative infection was defined as either being seropositive or having a history of COVID-19. Cumulative infection has increased from 2.0% in June 2021 (pre-Delta) to 5.3% in December 2021 (post-Delta). After the emergence of the Omicron, it has increased substantially during 2022 (16.9% in June and 39.0% in December). As of December 2022, 30% of those who were infected in the past were not aware of their infection. Results indicate that SARS-CoV-2 infection has rapidly expanded during the Omicron-variant epidemic among healthcare workers in Tokyo and that a sizable number of infections were undiagnosed.

Simulation of SARS-CoV-2 epidemic trends in Tokyo considering vaccinations, virus mutations, government policies and PCR tests.

The eighth wave of COVID-19 infection in the Tokyo area has brought daily confirmed cases to a new higher level. This paper aims to explain the previous seven epidemic waves and forecast the eighth epidemic trend of the area using agent-based modeling and extended SEIR denotation. Four key considerations are investigated in this research, that are: 1. Vaccination, 2. Virus mutations, 3. Governmental policies and 4. PCR tests. Our study finds that the confirmed cases in the previous seven epidemic waves were only the tip of the iceberg. Using data prior to December 1 2022, the eighth wave is expected to hover high in December 2022 and January 2023. Our research pioneers in the simulation of antibody declination on an individual level. Comparing the simulated results, we find that the arrival of new epidemic waves are related to the decline in the number of antibody possessors, especially the sixth and the seventh epidemic waves. Our simulation also suggests that faced with low severe and death rates, PCR tests would not make much difference to reduce overall infections. In this case, maintaining PCR tests to a low level helps to reduce both social cost and public anxiety. However, if faced with the opposite case, PCR tests should be adjusted to a higher level to detect early infections. Such level of PCR tests should be compatible with available medical resources.

How Hospitals Overcame Disruptions in the Early Stages of the COVID-19 Pandemic: A Case Study from Tokyo, Japan.

The COVID-19 pandemic has caused serious disruptions to health systems across the world. While the pandemic has not ended, it is important to better understand the resilience of health systems by looking at the response to COVID-19 by hospitals and hospital staff. Part of a multi-country study, this study looks at the first and second waves of the pandemic in Japan and examines disruptions experienced by hospitals because of COVID-19 and the processes through which they overcame those disruptions. A holistic multiple case study design was employed, and two public hospitals were selected for the study. A total of 57 interviews were undertaken with purposively selected participants. A thematic approach was used in the analysis. The study found that in the early stages of the pandemic, faced with a previously unknown infectious disease, to facilitate the delivery of care to COVID-19 patients while also providing limited non-COVID-19 health care services, the case study hospitals undertook absorptive, adaptive, and transformative actions in the areas of hospital governance, human resources, nosocomial infection control, space and infrastructure management, and management of supplies. The process of overcoming the disruptions caused by the pandemic was complex, and the solution to one issue often caused other problems. To inform preparations for future health shocks and promote resilience, it is imperative to further investigate both organizational and broader health system factors that build absorptive, adaptive, and transformative capacity in hospitals.

Accelerated cognitive decline after the COVID-19 pandemic in a community population of older persons with cognitive impairment: A 4-year time series analysis in the Tokyo Metropolis area.

AIM: The coronavirus disease 2019 (COVID-19) pandemic has led to lifestyle restrictions and might be associated with long-term changes in cognitive function. The aim of the present study was to elucidate the overall effect of the COVID-19 pandemic on the cognitive trajectory of a cohort of patients with cognitive impairment. METHODS: We enrolled 160 patients who had been making regular visits to a medical center for dementia. Cognitive function was assessed based on changes in scores on the Mini-Mental State Examination before and during the COVID-19 pandemic throughout a 4-year period. The trajectory of cognitive decline was determined by carrying out a time series analysis using a state-space model. RESULTS: Crude analysis showed that the Mini-Mental State Examination scores decreased from 20.9 ± 4.4 points (mean ± SD) at the time of the initial cognitive assessments to 17.5 ± 5.6 points at the time of the final assessments, and the decline rate was 1.15 ± 1.78 points per year (P < 0.0001). The time series analysis showed an accelerated cognitive trajectory after the COVID-19 outbreak, and the average decline in the Mini-Mental State Examination scores was 0.46 points (95% confidence interval 0.034-0.91) per year before the COVID-19 pandemic, and a steeper decline of 1.87 points (95% confidence interval 1.34-2.67) per year after the outbreak. CONCLUSIONS: The COVID-19 pandemic accelerated the rate of cognitive decline in patients with cognitive impairment fourfold in comparison with before the pandemic. Specific strategies designed for cognitively older people in the "new normal" will reconcile both requirements, reducing the risk of infection, and maintaining their physical and psychological well-being. Geriatr Gerontol Int 2023; 23: 200-204.

The Impact of Preventive Strategies Adopted during Large Events on the COVID-19 Pandemic: A Case Study of the Tokyo Olympics to Provide Guidance for Future Large Events.

This study aimed to analyze the impact of hosting large events on the spread of pandemics, taking Tokyo Olympics 2020 as a case study. A risk assessment method for the whole organization process was established, which could be used to evaluate the effectiveness of various risk mitigation measures. Different scenarios for Games participants and Japanese residents during the Tokyo Olympics were designed based on the infection control protocols proposed by the Olympic Committee and local governments. A modified Wells-Riley model considering the influence of social distance, masking and vaccination, and an SIQRV model that introduced the effect of quarantine and vaccination strategies on the pandemic spread were developed in this study. Based on the two models, our predicted results of daily confirmed cases and cumulative cases were obtained and compared with reported data, where good agreement was achieved. The results show that the two core infection control strategies of the bubble scheme and frequent testing scheme curbed the spread of the COVID-19 pandemic during the Tokyo Olympics. Among Games participants, Japanese local staff accounted for more than 60% of the total in positive cases due to their large population and most relaxed travel restrictions. The surge in positive cases was mainly attributed to the high transmission rate of the Delta variant and the low level of immunization in Japan. Based on our simulation results, the risk management flaws for the Tokyo Olympics were identified and improvement measures were investigated. Moreover, a further analysis was carried out on the impact of different preventive measures with respect to minimizing the transmission of new variants with higher transmissibility. Overall, the findings in this study can help policymakers to design scientifically based and practical countermeasures to cope with pandemics during the hosting of large events.

Novel indicator for the spread of new coronavirus disease 2019 and its association with human mobility in Japan.

The Japanese government adopted policies to control human mobility in 2020 to prevent the spread of severe acute respiratory syndrome coronavirus 2, which causes coronavirus disease 2019 (COVID-19). The present study examined the impact of human mobility on COVID-19 cases at the prefectural level in Japan by devising an indicator to have a relationship between the number of infected people and on human mobility. We calculated origin-destination travel mobility within prefectures in Japan from March 1st to December 31st, 2020, using mobile phone data. A cross-correlation function (CCF) was used to examine the relationship between human mobility and a COVID-19 infection acceleration indicator (IAI), which represents the rate of change in the speed of COVID-19 infection. The CCF of intraprefectural human mobility and the IAI in Tokyo showed a maximum value of 0.440 at lag day 12, and the IAI could be used as an indicator to predict COVID-19 cases. Therefore, the IAI and human mobility during the COVID-19 pandemic were useful for predicting infection status. The number of COVID-19 cases was associated with human mobility at the prefectural level in Japan in 2020. Controlling human mobility could help control infectious diseases in a pandemic, especially prior to starting vaccination.

Antibody response to third and fourth BNT162b2 mRNA booster vaccinations in healthcare workers in Tokyo, Japan.

BACKGROUND: Booster vaccinations against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are being promoted worldwide to counter the coronavirus disease 2019 (COVID-19) pandemic. In this study, we analyzed the longitudinal effect of the third BNT162b2 mRNA vaccination on antibody responses in healthcare workers. Additionally, antibody responses induced by the fourth vaccination were analyzed. METHODS: The levels of anti-spike (S) IgG and neutralizing antibody against SARS-CoV-2 were measured at 7 months after the second vaccination (n = 1138), and at 4 (n = 701) and 7 (n = 417) months after the third vaccination using an iFlash 3000 chemiluminescence immunoassay analyzer. Among the 417 participants surveyed at 7 months after the third vaccination, 40 had received the fourth vaccination. A multiple linear regression analysis was performed to clarify which factors were associated with the anti-S IgG and neutralizing antibody. Variables assessed included sex, age, number of days after the second or third vaccination, diagnostic history of COVID-19, and anti-nucleocapsid (N) IgG level. RESULTS: At 7 months after the third vaccination, antibody responses were significantly higher than those at the same time after the second vaccination. Unlike the second vaccination, age had no effect on the antibody responses induced by the third vaccination. Furthermore, the fourth vaccination resulted in a further increase in antibody responses. The multiple linear regression analysis identified anti-N IgG level, presumably associated with infection, as a factor associated with antibody responses. CONCLUSIONS: Our findings showed that BNT162b2 booster vaccinations increased and sustained the antibody responses against SARS-CoV-2.

Social contact patterns in Japan in the COVID-19 pandemic during and after the Tokyo Olympic Games.

Background: Social contact data in Japan have not been updated since 2011. The main objectives of this study are to report on newly collected social contact data, to study mixing patterns in the context of the COVID-19 pandemic, and to compare the contact patterns during and after mass events like the 2020 Olympic Games, which were held in 2021. Methods: We compared the number of contacts per day during and after the Olympic Games and on weekdays and weekends; we also compared them with a pre-COVID-19 pandemic social contact study in Japan. Contact matrices consisting of the age-specific average number of contacted persons recorded per day were obtained from the survey data. Reciprocity at the population level was achieved by using a weighted average. Results: The median number of contacts per day was 3 (interquartile range (IQR) = 1-6). The occurrence of the Olympic Games and the temporal source of data (weekday or weekend) did not change the results substantially. All three matrices derived from this survey showed age-specific assortative mixing patterns like the previous social contact survey. Conclusions: The frequency of social contact in Japan did not change substantially during the Tokyo Olympic Games. However, the baseline frequency of social mixing declined vs those collected in 2011.

Sustaining self-restraint until the middle of the COVID-19 pandemic in Tokyo.

We analyzed time-series changes in people's purpose-specific mobility characteristics owing to the COVID-19 pandemic in the Tokyo area of Japan, where only legally non-binding requests for self-restraint were enforced. A multiple regression analysis was conducted with the objective variable being the mobile population in the Tokyo area per 500 m square grid estimated from mobile spatial statistical data for 2 years from 10/01/2019 to 9/30/2021. This study period ranges from pre- to mid-pandemic. The explanatory variable was the number of buildings by type per 500 m square grid obtained from building statistical data to determine behavioral changes by mobility purpose. The analysis revealed that self-restraint was sustained until the middle of the COVID-19 pandemic in the Tokyo area regardless of the purpose of mobility and whether a state of emergency was declared.

Agent-based model using GPS analysis for infection spread and inhibition mechanism of SARS-CoV-2 in Tokyo.

Analyzing the SARS-CoV-2 pandemic outbreak based on actual data while reflecting the characteristics of the real city provides beneficial information for taking reasonable infection control measures in the future. We demonstrate agent-based modeling for Tokyo based on GPS information and official national statistics and perform a spatiotemporal analysis of the infection situation in Tokyo. As a result of the simulation during the first wave of SARS-CoV-2 in Tokyo using real GPS data, the infection occurred in the service industry, such as restaurants, in the city center, and then the infected people brought back the virus to the residential area; the infection spread in each area in Tokyo. This phenomenon clarifies that the spread of infection can be curbed by suppressing going out or strengthening infection prevention measures in service facilities. It was shown that pandemic measures in Tokyo could be achieved not only by strong control, such as the lockdown of cities, but also by thorough infection prevention measures in service facilities, which explains the curb phenomena in real Tokyo.

Influence of trip distance and population density on intra-city mobility patterns in Tokyo during COVID-19 pandemic.

This study investigates the influence of infection cases of COVID-19 and two non-compulsory lockdowns on human mobility within the Tokyo metropolitan area. Using the data of hourly staying population in each 500m×500m cell and their city-level residency, we show that long-distance trips or trips to crowded places decrease significantly when infection cases increase. The same result holds for the two lockdowns, although the second lockdown was less effective. Hence, Japanese non-compulsory lockdowns influence mobility in a similar way to the increase in infection cases. This means that they are accepted as alarm triggers for people who are at risk of contracting 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.

Inter-prefectural Travel and Network Connectedness During the COVID-19 Pandemic in Japan.

BACKGROUND: Increases in human mobility have been linked to rises in novel coronavirus disease 2019 (COVID-19) transmission. The pandemic era in Japan has been characterized by changes in inter-prefectural mobility across state of emergency (SOE) declarations and travel campaigns, but they have yet to be characterized. METHODS: Using Yahoo Japan mobility data extracted from the smartphones of more than 10 million Japanese residents, we calculated the monthly number of inter-prefectural travel instances, stratified by residential prefecture and destination prefecture. We then used this adjacency matrix to calculate two network connectedness metrics, closeness centrality and effective distance, that reliably predict disease transmission. RESULTS: Inter-prefectural mobility and network connectedness decreased most considerably during the first SOE, but this decrease dampened with each successive SOE. Mobility and network connectedness increased during the Go To Travel campaign. Travel volume between distant prefectures decreased more than travel between prefectures with geographic proximity. Closeness centrality was found to be negatively correlated with the rate of COVID-19 infection across prefectures, with the strength of this association increasing in tandem with the infection rate. Changes in effective distance were more visible among geographically isolated prefectures (Hokkaido and Okinawa) than among metropolitan, central prefectures (Tokyo, Aichi, Osaka, and Fukuoka). CONCLUSION: The magnitude of reductions in human mobility decreased with each subsequent state of emergency, consistent with pandemic fatigue. The association between network connectedness and rates of COVID-19 infection remained visible throughout the entirety of the pandemic period, suggesting that inter-prefectural mobility may have contributed to disease spread.