“…In Japan, the government introduced the slogan the "Three Cs," which referred to the recommendation to avoid "closed spaces with poor ventilation, " "crowded places with many people nearby, " and "close-contact settings, such as close-range, " and recommended that the public incorporate basic infection www.nature.com/scientificreports/ prevention measures into their lifestyles. As evidenced by the highest rate of mask use worldwide 16 , the Japanese population was disciplined, and every citizen was prepared for infection control, which is considered a step toward an era of living with COVID-19 17 . In addition, the first mutant strain of the SARS-COV-2 virus to attract worldwide attention, VOC-202012/01, showed an effective reproduction rate that was 43% to 90% higher than that of conventional strains but was not detected in Japan until December 25th, 2020 18,19 .…”