Validate Predictions as of August 1 and Generate Supposition
➡︎The change in the actual human flow from the end of July to the middle of September suggested that the human flow alone could not explain the subsequent changes in the infection rate and the effective reproduction number Rt.
Validate Predictions as of August 1 and Generate Supposition
➡︎Chart 2 shows a nonlinear estimate of the effective reproduction number for the period 6/1 to 7/31, and the actual and estimated values are in good agreement.
➡︎Using this model to estimate the change of infection rate and Rt after 8/1, the change of infection rate and Rt from mid-August are overestimated.
➡︎It was suggested that the estimation based on human flow alone overestimates vaccine effectiveness and other factors.
Validate Predictions as of August 1 and Generate Supposition
➡︎As a result of examining the estimated number of new positive cases by the SEIR model using the observed data up to 8/1 and the estimated change of infection rate after 8/2, it was suggested as a supposition that risk aversion and other behaviors that could not be predicted from human flow alone occurred.
➡︎There is a possible need to look at the characteristics of the people who act, as well as their behavioral patterns.
Summary
・Infections declined sharply in the second half of August 2021. An attempt was made to estimate the reason from the data.
・Using the number of people staying in downtown Tokyo at night, people coming in from outside of Tokyo, and the vaccination rate, we were able to accurately estimate the effective reproduction number, which represents the infectivity per capita. Also, however, when we estimated the post-August period using a model trained on data up to 8/1, the number of infected people in mid-August was overestimated.
・This is due to the fact that the model overestimated the rebound of the number of staying people in the second half of August, but this may have been due to a change in the makeup of the people staying in the area.
・Although the number of staying people increased after the second half of August, unvaccinated individuals avoided downtown areas at night or avoided activities with a high risk of infection, which may be one of the assumed reasons for the rapid decrease after summer.
