  The threat of the new coronavirus (COVID-19) is increasing. Regarding the
difference in the infection rate observed in each region, in addition to
studies seeking the cause due to differences in the social distance (population
density), there is an increasing trend toward studies seeking the cause due to
differences in social capital. However, studies have not yet been conducted on
whether social capital could influence the infection rate even if it controls
the effect of population density. Therefore, in this paper, we analyzed the
relationship between infection rate, population density, and social capital
using statistical data for each prefecture. Statistical analysis showed that
social capital not only correlates with infection rates and population
densities but still has a negative correlation with infection rates controlling
for the effects of population density. Besides, controlling the relationship
between variables by mean age showed that social capital had a greater
correlation with infection rate than population density. In other words, social
capital mediates the correlation between population density and infection
rates. This means that social distance alone is not enough to deter coronavirus
infection, and social capital needs to be recharged.
