  A transmission interval for an infectious disease is important to understand
epidemic processes in complex networks. The transmission interval is defined as
a time interval between one person's infection and their infection to another
person. To study statistical properties of transmission intervals, we analyze a
COVID-19 dataset of confirmed cases in Republic of Korea that has been
collected for two years since the confirmation of the first case on 19 January
2020. Utilizing demographic information of confirmed individuals, such as sex,
age, residence location, and the nature of relation between infectors and
infectees, we find that transmission intervals are rarely affected by sexes,
but they tend to have larger values for the youngest and oldest age groups than
other groups. We also find some metropolitan cities or provinces with
relatively larger (smaller) transmission intervals than other locations. These
empirical findings might help us to better understand dynamical mechanisms of
epidemic processes in complex social systems.
