Assessing the regional impact of Japan's COVID-19 state of emergency declaration: A population-level observational study using social networking services

Daisuke Yoneoka, Shoi Shi, Shuhei Nomura, Yuta Tanoue, Takayuki Kawashima, Akifumi Eguchi, Kentaro Matsuura, Koji Makiyama, Shinya Uryu, Keisuke Ejima, Haruka Sakamoto, Toshibumi Taniguchi, Hiroyuki Kunishima, Stuart Gilmour, Hiroshi Nishiura, Hiroaki Miyata*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


Objective On 7 April 2020, the Japanese government declared a state of emergency in response to the novel coronavirus outbreak. To estimate the impact of the declaration on regional cities with low numbers of COVID-19 cases, large-scale surveillance to capture the current epidemiological situation of COVID-19 was urgently conducted in this study. Design Cohort study. Setting Social networking service (SNS)-based online survey conducted in five prefectures of Japan: Tottori, Kagawa, Shimane, Tokushima and Okayama. Participants 127 121 participants from the five prefectures surveyed between 24 March and 5 May 2020. Interventions An SNS-based healthcare system named COOPERA (COvid-19: Operation for Personalized Empowerment to Render smart prevention And care seeking) was launched. It asks questions regarding postcode, personal information, preventive actions, and current and past symptoms related to COVID-19. Primary and secondary outcome measures Empirical Bayes estimates of age-sex-standardised incidence rate (EBSIR) of symptoms and the spatial correlation between the number of those who reported having symptoms and the number of COVID-19 cases were examined to identify the geographical distribution of symptoms in the five prefectures. Results 97.8% of participants had no subjective symptoms. We identified several geographical clusters of fever with significant spatial correlation (r=0.67) with the number of confirmed COVID-19 cases, especially in the urban centres of prefectural capital cities. Conclusions Given that there are still several high-risk areas measured by EBSIR, careful discussion on which areas should be reopened at the end of the state of emergency is urgently required using real-time SNS system to monitor the nationwide epidemic.

Original languageEnglish
Article numbere042002
JournalBMJ open
Issue number2
Publication statusPublished - 2021 Feb 15
Externally publishedYes


  • COVID-19
  • epidemiology
  • health policy
  • infectious diseases

ASJC Scopus subject areas

  • Medicine(all)


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