In this outbreak, the fomite transmission of norovirus between people occurred mainly via interactive behaviors such as hand shaking and waiters serving guests. Because it was assumed that the guests did not shake hands with those from other parties, hand shaking behavior merely influenced the regional distribution of the infection risk at each table. In contrast, the waiters’ serving behavior was not limited to single tables, which resulted in virus transmission between different tables. The waiter who initially carried the virus acted as a mobile virus source by which clean surfaces were contaminated, whereas other waiters acted as mobile media by which viruses were transmitted between surfaces. Thus, the overall infection risk distributions varied among the various serving pathway patterns (Figure 2 and Figure S1).