1.Infection model by SEIR mathematical model and AI optimization method
The SEIR model, which takes into account population flow and AI technology (evolutionary optimization + quasi-Newton method), were used to optimize infection model estimation within and between three age groups (0-39 years, 40-59 years, and 60 years or older). The number of positive patient inflows from outside the prefecture was estimated from mobile spatial statistics data (NTT Docomo) and LocationMind xPop*1 and incorporated into the model, and the model was trained from data from March 1 to October 30, 2021.
2.Effects of vaccine and behavior change
・Vaccine efficacy was 33% for the 2nd and 75% for the 3rd dose against the Omicron variant. The Omicron variant was assumed to have started to infect 5 people via community spread on December 10.
・Measured values are used for changes in the effective reproduction number and the number of populations flows from March 1 to December 18. The effective reproductions number and risk of inflow of infected persons were estimated assuming that the population remaining in downtown areas (13:00, 19:00, and 21:00) and the population coming from outside Tokyo were at the same levels as in November after December 19.
・Diminishing vaccine efficacy was assumed to diminish to 50% in 180 days. Booster vaccinations were to begin on December 1 for medical personnel 180 days after the 2nd vaccination, 210 days after January 15 for the elderly, and 240 days after February 1 for those under 60 years of age.
・Resurgence of SARS-CoV-2 Infection in a Highly Vaccinated Health System Workforce, DOI: 10.1056/NEJMc2112981, The new England journal of medicine
・COVID vaccines protect against Delta, but their effectiveness wanes, doi: httpss://doi.org/10.1038/d41586-021-02261-8, Nature
・Comparative Effectiveness of Moderna, Pfizer-BioNTech, and Janssen (Johnson & Johnson) Vaccines in Preventing COVID-19 Hospitalizations Among Adults Without Immunocompromising Conditions — United States, March–August 2021, CDC vol.70, 17, Sep. 2021
・National Institute of Infectious Diseases, Mutated variant B.1.1.529 (the Omicron variant) of SARS-CoV-2 (5th report), 2021
3.Tokyo suburbs agent base model
We constructed a model represented by 1,348 agents in 2 cities based on the household structure of a Tokyo suburb, and restricted workplaces, restaurants, and event venues by vaccination proof, and measured the rate of change in Rt from 500 trials each. Companions to eat and drink together were assumed to be chosen randomly from a network of friends (the number of friends was a power-law distributed Galton-Watson network).
*1 "LocationMind xPop" data is data that NTT DOCOMO collectively and statistically processes from mobile phone location information sent with permission from users of applications* provided by NTT DOCOMO. Location information is GPS data (latitude and longitude information) that is measured at a minimum of every five minutes, and does not contain information that identifies an individual. DOCOMO Map Navi Service (map application, local guide) and some other applications