Before revision:  A good correlation was observed between the spread and decay durations (R2=0.37) . However, some exceptions were observed in prefectures that are adjacent to primary prefectures (e.g., Tokyo, Osaka, Aichi, and Fukuoka) and in areas where people returned from foreign countries, which were defined origins of cluster infections . Excluding these prefectures, population density is shown to be the primary factor affecting spread and decay patterns, with correlations of 0.52 and 0.76, respectively.
After revision:  A good correlation was observed between the spread and decay durations (R2=0.37) . However, some exceptions were observed in prefectures that are adjacent to primary prefectures (e.g., Tokyo, Osaka, Aichi, and Fukuoka) and in areas where people returned from foreign countries, which were defined origins of cluster infections . Excluding these prefectures, population density is shown to be a major factor affecting the spread and decay patterns, with correlations of 0.52 and 0.76, respectively.