Background: In February 2020, a coronavirus disease 2019 (COVID-19) outbreak was reported in fitness centers in Cheonan, Korea. Methods: From February 24 to March 13, an epidemiological investigation was conducted on the fitness center outbreak. All those who were screened were tested for severe acute respiratory syndrome coronavirus-2 (SARS CoV-2) using real-time reverse transcriptase polymerase chain reaction. Contacts were traced and self-isolated for 14 days. We determined the epidemiological characteristics of confirmed cases of SARS-CoV-2 infection, and estimated the time-dependent reproduction number to assess the transmission dynamics of the infection. Results: A total of 116 cases were confirmed, and 1,687 contacts were traced. The source cases were 8 Zumba instructors who led aerobics classes in 10 fitness centers, and had the largest average number of contacts. A total of 57 Zumba class participants, 37 of their family members, and 14 other contacts were confirmed as cases. The attack rate was 7.3%. The contacts at Zumba classes and homes had a higher attack rate than other contacts. The mean serial interval (± standard deviation) were estimated to be 5.2 (± 3.8) days. The timedependent reproduction number was estimated to be 6.1 at the beginning of the outbreak, but it dropped to less than 1, 2 days after the epidemiological investigation was launched. Conclusion: The results suggest that the COVID-19 outbreak was effectively contained with rigorous contact tracing, isolating, and testing in combination with social distancing without a lock-down.

ObjectivesTesticular torsion (TT) is a pediatric surgical emergency that requires prompt treatment. This study investigated the feasibility of point‐of‐care ultrasound (POCUS) for diagnosing TT in the pediatric emergency department (ED).MethodsWe retrospectively reviewed the medical records of patients, aged 18 years or younger, who visited a university‐affiliated hospital pediatric ED with acute scrotal pain without trauma history and underwent diagnostic ultrasounds between January 2010 and October 2022.ResultsThis study included 731 patients (median age: 9 years), Of these, 315 (43%) were in the POCUS‐performed group: 188 in the POCUS‐only group, and 127 in the POCUS‐and‐RADUS group. The other 416 patients (56.9%) were in the RADUS‐only group. In total, 45 patients (6.2%) were diagnosed with TT (19 in the POCUS‐performed group and 26 in the RADUS‐only group). The sensitivity, specificity, and positive and negative predictive values of POCUS for diagnosing TT were 94.7%, 92.9%, 46.2%, and 99.6%, respectively. The median time to perform POCUS was shorter than RADUS (23 versus 61 minutes, P < .001). The POCUS‐performed group had a shorter ED length of stay than the RADUS‐only group (93 versus 170 minutes, P < .001). Among the patients diagnosed with TT, performing POCUS first did not significantly delay the ED process, including time to operation (250 versus 205 minutes, P = .142).ConclusionsFor patients with acute scrotal pain, evaluation performed by pediatric emergency physicians using POCUS performs well in screening TT, and can decrease length of stay in the ED.