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. The absolute humidity also affected the spread duration (R2  = 0.40).
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 the primary factor affecting spread and decay patterns, with R2=0.39 (p<0.05) and 0.42 (p<0.05), respectively, approximately corresponding to social distancing. The maximum absolute humidity was found to affect the decay duration normalized by the population density (R2 = 0.40).