著者
Shohei Nagata Tomoki Nakaya Yu Adachi Toru Inamori Kazuto Nakamura Dai Arima Hiroshi Nishiura
出版者
Japan Epidemiological Association
雑誌
Journal of Epidemiology (ISSN:09175040)
巻号頁・発行日
pp.JE20200625, (Released:2021-04-03)
参考文献数
14

Background: As the COVID-19 pandemic spread, the Japanese government declared a state of emergency on April 7, 2020 for seven prefectures, and on April 16, 2020 for all prefectures. The Japanese Prime Minister and governors requested people to adopt self-restraint behaviors, including working from home and refraining from visiting nightlife spots. However, the effectiveness of the mobility change due to such requests in reducing the spread of COVID-19 has been little investigated. The present study examined the association of the mobility change in working, nightlife, and residential places and the COVID-19 outbreaks in Tokyo, Osaka, and Nagoya metropolitan areas in Japan.Methods: First, we calculated the daily mobility change in working, nightlife, and residential places compared to the mobility before the outbreak using mobile device data. Second, we estimated the sensitivity of mobility changes to the reproduction number by generalized least squares.Results: Mobility change had already started in March, 2020. However, mobility reduction in nightlife places was particularly significant due to the state of emergency declaration. Although the mobility in each place type was associated with the COVID-19 outbreak, the mobility changes in nightlife places were more significantly associated with the outbreak than those in the other place types. There were regional differences in intensity of sensitivity among each metropolitan area.Conclusions: Our findings indicated the effectiveness of the mobility changes, particularly in nightlife places, in reducing the outbreak of COVID-19.
著者
Daisuke Yoneoka Takayuki Kawashima Yuta Tanoue Shuhei Nomura Keisuke Ejima Shoi Shi Akifumi Eguchi Toshibumi Taniguchi Haruka Sakamoto Hiroyuki Kunishima Stuart Gilmour Hiroshi Nishiura Hiroaki Miyata
出版者
Japan Epidemiological Association
雑誌
Journal of Epidemiology (ISSN:09175040)
巻号頁・発行日
pp.JE20200150, (Released:2020-05-30)
参考文献数
23
被引用文献数
10

BackgroundThe World Health Organization declared the novel coronavirus outbreak (COVID-19) to be a pandemic on March 11, 2020. Large-scale monitoring for capturing the current epidemiological situation of COVID-19 in Japan would improve preparation for and prevention of a massive outbreak.MethodsA chatbot-based healthcare system named COOPERA (COvid-19: Operation for Personalized Empowerment to Render smart prevention And care seeking) was developed using the LINE app to evaluate the current Japanese epidemiological situation. LINE users could participate in the system either though a QR code page in the prefecture’s website, or a banner at the top of the LINE app screen. COOPERA asked participants questions regarding personal information, preventive actions, and non-specific symptoms related to COVID-19 and their duration. We calculated daily cross correlation functions between the reported number of infected cases confirmed by PCR and the symptom-positive group captured by COOPERA.ResultsWe analyzed 206,218 participants from three prefectures reported between March 5 and 30, 2020. The mean (standard deviation) age of participants was 44.2 (13.2). No symptoms were reported by 96.93% of participants, but there was a significantly positive correlation between the reported number of COVID-19 cases and self-reported fevers, suggesting that massive monitoring of fever might help to estimate the scale of the COVID-19 epidemic in real time.ConclusionsCOOPERA is the first real-time system being used to monitor trends in COVID-19 in Japan, and provides useful insights to assist political decisions to tackle the epidemic.
著者
Daisuke Yoneoka Takayuki Kawashima Yuta Tanoue Shuhei Nomura Keisuke Ejima Shoi Shi Akifumi Eguchi Toshibumi Taniguchi Haruka Sakamoto Hiroyuki Kunishima Stuart Gilmour Hiroshi Nishiura Hiroaki Miyata
出版者
Japan Epidemiological Association
雑誌
Journal of Epidemiology (ISSN:09175040)
巻号頁・発行日
vol.30, no.8, pp.362-370, 2020-08-05 (Released:2020-08-05)
参考文献数
23
被引用文献数
10

Background: The World Health Organization declared the novel coronavirus outbreak (COVID-19) to be a pandemic on March 11, 2020. Large-scale monitoring for capturing the current epidemiological situation of COVID-19 in Japan would improve preparation for and prevention of a massive outbreak.Methods: A chatbot-based healthcare system named COOPERA (COvid-19: Operation for Personalized Empowerment to Render smart prevention And care seeking) was developed using the LINE app to evaluate the current Japanese epidemiological situation. LINE users could participate in the system either though a QR code page in the prefectures’ websites or a banner at the top of the LINE app screen. COOPERA asked participants questions regarding personal information, preventive actions, and non-specific symptoms related to COVID-19 and their duration. We calculated daily cross correlation functions between the reported number of infected cases confirmed using polymerase chain reaction and the symptom-positive group captured by COOPERA.Results: We analyzed 206,218 participants from three prefectures reported between March 5 and 30, 2020. The mean age of participants was 44.2 (standard deviation, 13.2) years. No symptoms were reported by 96.93% of participants, but there was a significantly positive correlation between the reported number of COVID-19 cases and self-reported fevers, suggesting that massive monitoring of fever might help to estimate the scale of the COVID-19 epidemic in real time.Conclusions: COOPERA is the first real-time system being used to monitor trends in COVID-19 in Japan and provides useful insights to assist political decisions to tackle the epidemic.
著者
Fuminari Miura Ryota Matsuyama Hiroshi Nishiura
出版者
Japan Epidemiological Association
雑誌
Journal of Epidemiology (ISSN:09175040)
巻号頁・発行日
pp.JE20170040, (Released:2018-03-31)
参考文献数
34
被引用文献数
12

Background: Foodborne norovirus outbreak data in Japan from 2005–2006, involving virological surveillance of all symptomatic and asymptomatic individuals, were reanalyzed to estimate the asymptomatic ratio of norovirus infection along with the risk of infection and the probability of virus shedding.Methods: Employing a statistical model that is considered to capture the data-generating process of the outbreak and virus surveillance, maximum likelihood estimation of the asymptomatic ratio was implemented.Results: Assuming that all norovirus outbreaks (n = 55) were the result of random sampling from an identical distribution and ignoring genogroup and genotype specificities, the asymptomatic ratio was estimated at 32.1% (95% confidence interval [CI], 27.7–36.7). Although not significant, separate estimation of the asymptomatic ratio of the GII.4 genotype appeared to be greater than other genotypes and was estimated at 40.7% (95% CI, 32.8–49.0).Conclusion: The present study offered the first explicit empirical estimates of the asymptomatic ratio of norovirus infection in natural infection settings. The estimate of about 30% was consistent with those derived from volunteer challenge studies. Practical difficulty in controlling GII.4 outbreaks was supported by the data, considering that a large estimate of the asymptomatic ratio was obtained for the GII.4 genotype.
著者
HIROSHI NISHIURA MASAYUKI KAKEHASHI
出版者
Japanese Society of Tropical Medicine
雑誌
Tropical Medicine and Health (ISSN:13488945)
巻号頁・発行日
vol.33, no.3, pp.127-132, 2005 (Released:2005-12-03)
参考文献数
32
被引用文献数
1 1

To estimate the time-dependent transmission potential of primary pneumonic plague (PPP), we analyzed historical records from six outbreaks. Based on contact investigation information (source of infection information) of three outbreaks, we generalized the probability density function of the serial interval with a Gamma distribution using maximum likelihood estimations. Furthermore, we used a likelihood-based approach to estimate effective reproduction numbers at time t, Rt, incorporating records from the remaining three outbreaks by assuming independence within unknown contact networks. According to our estimates, the Rt of PPP during the initial phases of each epidemic were roughly in the order of 1.3 (95% confidence interval (CI): 0.0-4.3) in Oakland, 1.4 (0.0-4.6) in Rangoon and 6.5 (0.0-16.0) in Ecuador. The expected values of Rt were shown to slightly exceed unity, even in latter stages. While declining trends in Rt were observed in Oakland and Ecuador, no such trend was observed in Rangoon. The findings suggest that the three outbreaks investigated could have been accompanied by demographic stochasticity. The statistical usefulness of the transformation procedure, even with a small number of recorded cases available, was demonstrated, and the expected responses to bioterrorism using Yersinia pestis were discussed.