“…They found that the infection rate showed a rising trend from 11.1% in period 1 to 19.2% and 20.0% in periods 2 and 3, respectively. The authors speculated that one important factor of the rising trend in infection rate was the change in definition used for close contacts in Japan [6]. In addition, the variants differed between the periods [7] and some variants, such as the Omicron, have been shown to have strong immune escape [8].…”