Infection Simulation based on Proposed Human Behavior Models derived from SNS and Press Data #5

Date: 2021.07.27
Researcher: Satoshi Kurihara
Organization: Faculty of Science and Technology, Keio University

Projected number of positive cases in the short term

If the effect of the 4th state of emergency is greater than the priority measures to prevent the spread of infectious disease, the number of positive cases will rise for a short period and then decrease. On the other hand, if the effect is less than that, the increase is continued.

Projected number of seriously ill patients

If the effect of the 4th state of emergency is greater than the priority measures to prevent the spread of infectious disease, the number of seriously ill patients will rise until mid-August and then decrease. On the other hand, if the effect is less than that, the increase is continued.

Parameter setting (1) Vaccination

The parameters for the simulation are set as follows.

Vaccination
■　~ Aged 14
　➡　No vaccination
■　Aged 15 ~ 39
　➡　Pfizer + Moderna
　➡　Final vaccination rate 75%
■　Aged 40 ~ 64
　➡　Pfizer + Moderna
　➡　Final vaccination rate 75%
■　Aged 65 ~
　➡　Pfizer
　➡　Final vaccination rate 85%

Parameter setting (2) Serious illness rate

The parameters for the simulation are set as follows.

From the 11th meeting of the COVID-19 advisory board of Ministry of Health, Labour and Welfare (October 22, 2020)[1]
※1 For Delta variant, the same values are used as Alpha variant
※2 2 Reference values when medical capacity is not tightened
※3 The serious illness rate in the case of vaccination is assumed to be 1/10 of the above

Mobile Spatial Statistics data

In the 4th state of emergency, the decrease in the number of people are not confirmed as in the previous declarations.

・Mobile spatial statistics were used to identify changes in the population flow in downtown areas within the region where the state of emergency was declared.
・During past state of emergency, we have seen a significant reduction in human flow in each of the areas where the state of emergency was declared. The effect (reduction in the number of people in the region) was strongest at the time of the 1st declaration, with no significant difference in effect between the 2nd and 3rd.
・In the 4th state of emergency, the same effect on reducing the number of people are not seen as in the past, and all areas are showing the same human flow as before the declaration (during priority measures).
・On the other hand, in areas where the state of emergency has been lifted, or where the state has been switched to priority measures, the human flow has been confirmed to be the same or higher than before.