creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. COVID-19 epidemic level and gradually eased the intensities of social distancing from high (until April 18) to moderate (April 19-29) and social distancing in life (since April 30). While maintaining strict quarantine, massive screening, and isolation, the government attempted to revitalize the economy with mitigated social distancing. However, many confirmed cases were identified during this policy transition. At the end of the moderate-intensity social distancing, people's interests in leisure (taking trips, eating at restaurants, visiting bars, and lodging) increased markedly according to the Internet search trend (Fig. 1) . 3 The internet search trend is to check the daily number of searches for the specific search terms and set the maximum search volume to 100 during the search period to calculate the relative change of the day, using the analysis program, NAVER (NAVER Corp., Seoul, Korea). After the serial interval (7-8 days) from the mitigating transition, the number of confirmed cases again began to increase, particularly in young adults. 4 These cases, which could represent a second wave in Korea, have spread around nightclubs in Itaewon, a frequent foreign tourist destination. They have spread rapidly to the families and coworkers, given the socially active nature of young people, thereby spreading to other regions. The resurgence, which started at nightclubs, is feared to progress to a larger outbreak, as it has ignited in distribution centers. 2
Some prerequisites to implementing a mitigation strategy successfully are as follows. Special groups that can be a vulnerable point of infection in the community must be considered. In Korea, such foci were mass-gathering churches, call centers, distribution centers, indoor sports facilities and nightclubs. 2,5 A second wave could start with delayed detection and reporting of these social vulnerabilities. When mitigating social distancing measures, a management plan for vulnerable facilities and locations should be reinforced. It is necessary to guide and support to keep the standards such as strengthened mask wearing, maintaining individual distancing, improving ventilation facilities, and limiting the number of attendees. In addition, it is even more important to monitor whether these principles are being met and provide feedback.