令和2年度電気・電子・情報関係学会四国支部連合大会 講演論文集 (愛媛大学)
2020 SHIKOKU-SECTION JOINT CONVENTION RECORD OF THE INSTITUTES OF ELECTRICAL AND RELATED ENGINEERS (EHIME UNIV.)

1-19
Examination of the Appropriate Time of Movement Restrictionof People in COVID-19
Naohide. Hashimoto

1.

Shu. Sumimoto
Yoko. Uwate(Tokushima University)

Yoshifumi. Nishio

Introduction
COVID-19 is spreading worldwide, in major cities in Japan, thegovernment set up a countermeasures headquarter from March 25,
2020, issued an emergency declaration from April 8, and canceled
it on May 25. The declaration of emergency restricted The
movement of people and temporarily stopped the spread ofinfection. In this study, we examine when the govermment shoud

Figure 2: Changes in the cumulative number of infected people.

limit the movement of people to minimize the spread of virus.
Figure 3 shows the change in the cumulative number of infected2.

Proposed method and conditions

people due to the difference of the start date of movement

The target of analysis is Tokyo (population 13 million), and therestrictions. The vertical axis shows the ratio based on theSEIR model, which is often used for infectious disease analysis,cumulative number of infected people when the movement wasused for the expanded analysis of COVID-19. The SEIR model

restricted on March 25. The horizontal axis shows the movement

divides the total population into four groups (non-infected,restriction start date.

exposed, infected, cured) and shows increase or decrease in eachgroups. The transition rate from non-infected to exposed is α = 0.1,
and the infectious rate β = 0.1. We applied the SEIR model bymultiplying α and β by the ratio of the amount of movementpublished by apple1). Since the movement limit is likely to be highduring the period from March 25 to June 20, use only the values
for that period, and set the movement ratio to 1 for the otherFigure 3: Changes in the cumulative number of infected people

periods (Fig1). Here, we consider the time when the Japanese

due to different movement control start dates.

government started to work on movement restrictions (March 25)
as the time of substantial movement restrictions, and examined theFrom Figure 3, it can be seen that the start date of movement

difference in the number of infected people when changing therestriction is March 28, the number of infected people is thestart time of movement restrictions.

smallest, and if the movement restriction start time is too late or
too early, the damage will increase about 5%.

4.

Conclusion

In this study, we examined the optimal timing of movement
regulation to prevent the spread of COVID-19 infection using
SEIR model. As a result of the analysis, it was found that theFigure 1: Change in the amount of movement.

3.

Simulation results

The cumulative number of infected persons obtained from theSEIR model is shown in Fig. 2. It can be seen that the cumulative
number of infected people will eventually increase to about 5,200
if the movement restrictions are entered on March 25.

number of infected people could be minimized by having
restricted movement on March 28.

5.

Reference1)

Mobility Trend Report (apple)
https://www.apple.com/covid19/mobility