Setup
■Analysis in Tokyo
■Gradual recovery to "pre-pandemic socio-economic activity level" over 3 months from early November
■Image of this configuration
■After this November: Removing the requests for shorter hours at restaurants, serving alcoholic beverages OK, event restrictions removed
■After February next year: People will gradually stop wearing masks
■Maximum number of new infections per day that people can tolerate: 10,000 (assuming a medical capacity 1.5 times the current one)
■Basic reproduction number: 3, 3.75, 5, 6
■The value that the Fujii-Nakata team thinks is most plausible at this point is 3.75 (evidence: "Steady State Contact Rate Parameters" in this document)
■Vaccination applicants: About 80% of the total population <92% elderly, 80% aged 13-64, 0% aged 12 and under>
■Assumptions of effects of vaccination on infection prevention: 45% for the 1st dose, 75% for the 2nd dose
■Assuming that measures are effectively taken as needed to limit the reduction of effects of vaccination on infection prevention
■Seasonality: Using the Sine function, the maximum value of the contact rate parameter in winter is set to 1.8 times the minimum value in summer
■Future rates of serious illness, deaths, and hospitalizations
■Reflects the impact of the spread of antibody cocktails, the spread of oral medicines, the increase in breakthrough infections, and the increase in the proportion of underage infections in the overall judgment
Change from the previous settings (2 weeks ago)
■Basic reproduction number: 3.75
■Previously was 4
■Decided that the infectivity of the Delta variant was overestimated in the August/September analysis. In addition, some of the factors that contributed to the rapid decline in infections since late August suggest that herd immunity is closer to being achieved than previously thought
Evidence: "Factors behind the infection decrease in Tokyo: quantitative analysis" to be completed in the near future
■The model's contact rate parameters are assumed to remain at a low level until the end of October
■Previously, we had assumed that the contact rate parameter would rise sharply after the lifting, but there is no indication that this is the case
■Contact rate parameters gradually increased after the lifting of previous declarations
■Assuming a gradual recovery to pre-pandemic socio-economic activity over 3 months from early November
■Previous assumption was six months from the end of September. Assuming that if the infection situation is limited until the end of October, people will seek early recovery.
■Seasonal (360-day cycle) parameter: 1.8
■Previously was 1.2
■Changed to take into account (albeit incomplete) the results of an analysis showing that periodicity (120-day cycle) may explain about 50% of the decrease in infections from the second half of August ("Factors behind the infection decrease in Tokyo")
Points to keep in mind
■The number of cumulative deaths considers only “deaths due to COVID-19 infection”
■It does not take into consideration how strengthening the medical system for COVID-19 will lead to other conventional medical limitations and how much the limitations will increase the number of deaths from other causes
■It does not take into consideration the possibility that the number of suicides will increase due to the prolonged stagnation of social and economic activities due to the repeated declarations of state of emergency
■Batista, Fujii, and Nakata (2021) "COVID-19 and Suicides in Japan" contains the estimation of the additional suicide so far due to the COVID-19 pandemic
■The estimation of the number of seriously ill patients and deaths gives an incomplete consideration to the following factors
■If the proportion of newly infected people with breakthrough infections increases significantly, it would result in a decrease in the serious illness rate and mortality rate of all newly infected patients. This impact is only incompletely considered in this analysis
