PMC:2854337 / 10531-13453
Annnotations
{"target":"https://pubannotation.org/docs/sourcedb/PMC/sourceid/2854337","sourcedb":"PMC","sourceid":"2854337","source_url":"https://www.ncbi.nlm.nih.gov/pmc/2854337","text":"Study area and population structure of the IBM\nSapporo city, the capital of Hokkaido in Japan, was chosen as the targeted area because Sapporo city has a number of characteristics that make it suitable for simulating the spread of infection, including relatively small daily influxes and outflows of people compared with other major cities in Japan [28]. The National Census of Japan [28, 29] was used as the source of data on the age structure, resident population for each ward, household composition, places of schooling and work, and mode of transportation. The School Basic Survey [30] was the source of data on the number of schools and the enrollment rate at college, while the Employment Status Survey [31] provided the employment rate.\nSapporo city, which had a population of 1,880,863 in 2005 [28], is one of the ordinance-designated metropolis cities in Japan and is divided into ten wards as administrative units [32]. There is a substantial difference in the density of population among wards. There are also many commuters to school and work between wards during the daytime, which leads to the mass movement of people on a daily basis [28]. To simulate the situations of an influenza epidemic on a realistic basis, we adopted an IBM that can reflect the heterogeneous population structure for the targeted area, in which each individual was assigned his/her personal information, such as age, household, residence district, social activity group, and casual contact group. The age structure in Sapporo city [28] is shown in Fig. 1. The distribution of household size was determined on the basis of the National Census of Japan data [28], where each household was assumed to consist of at least one adult aged ≥19 years.\nFig. 1 Age distribution of Sapporo city [28]\nWe specified five categories of social activity groups that an individual may belong to according to age: playgroup (3–6 years), elementary school (7–12 years), high school (13–18 years), college group (19–22 years), and work group (19–64 years). The age-specific rates of the enrollment of college students and employment were determined based on data in the School Basic Survey [30] and the Employment Status Survey [31]. The size of social activity groups was assumed to be smaller than their actual size so that individuals in a group could come into close contact with each other and transmit the influenza virus among them.\nTwo kind of untraceable casual contact groups were considered: a low-risk group who came into contact with other people at markets, in the neighborhoods, etc. and a high-risk group who used public transportation facilities, such as crowded trains and buses. The ratio of high-risk casual contact groups was set at 38% on average in all casual contact groups based on a census of the mode of transportation [29]. All casual contact groups were composed afresh twice a day with a size of 20 individuals on average.","divisions":[{"label":"title","span":{"begin":0,"end":46}},{"label":"p","span":{"begin":47,"end":744}},{"label":"p","span":{"begin":745,"end":1779}},{"label":"figure","span":{"begin":1735,"end":1779}},{"label":"label","span":{"begin":1735,"end":1741}},{"label":"caption","span":{"begin":1742,"end":1779}},{"label":"p","span":{"begin":1742,"end":1779}},{"label":"p","span":{"begin":1780,"end":2409}}],"tracks":[]}