Background The military was one of the first groups in Korea to complete mass vaccination against the coronavirus disease 2019 (COVID-19) due to their high vulnerability to COVID-19. To confirm the effect of mass vaccination, this study analyzed the patterns of confirmed cases within Korean military units. Methods From August 1 to September 15, 2021, all epidemiological data regarding confirmed COVID-19 cases in military units were reviewed. The number of confirmed cases in the units that were believed to have achieved herd immunity (i.e., ≥ 70% vaccination) was compared with the number of cases in the units that were not believed to have reached herd immunity (< 70% vaccination). Additionally, trends in the incidence rates of COVID-19 in the military and the entire Korean population were compared. Results By August 2021, 85.60% of military personnel were fully vaccinated. During the study period, a total of 174 COVID-19 cases were confirmed in the 39 units. More local transmission (herd immunity group vs. non-herd immunity group [%], 1 [0.91] vs. 39 [60.94]) and hospitalizations (12 [11.01] vs. 13 [27.08]) occurred in the units that were not believed to have achieved herd immunity. The percentage of fully vaccinated individuals among the confirmed COVID-19 cases increased over time, possibly due to the prevalence of the delta variant. Nevertheless, the incidence rate remained lower in military units than in the general Korean population. Conclusion After completing mass vaccination, the incidence rates of COVID-19 infection in the military were lower than those in the national population. New cluster infections did not occur in vaccinated units, thereby suggesting that herd immunity has been achieved in these military units. Further research is needed to determine the extent to which levels of non-pharmacological intervention can be reduced in the future.

Background Due to the higher transmissibility and increased immune escape of the omicron variant of severe acute respiratory syndrome coronavirus 2, the number of patients with coronavirus disease 2019 (COVID-19) has skyrocketed in the Republic of Korea. Here, we analyzed the change in trend of the number of confirmed COVID-19 cases in the Korean military after the emergence of the omicron variant on December 5, 2021. Methods An interrupted time-series analysis was performed of the daily number of newly confirmed COVID-19 cases in the Korean military from September 1, 2021 to April 10, 2022, before and after the emergence of the omicron variant. Moreover, the daily number of newly confirmed COVID-19 cases in the Korean military and in the population of Korean civilians adjusted to the same with military were compared. Results The trends of COVID-19 occurrence in the military after emergence of the omicron variant was significantly increased (regression coefficient, 23.071; 95% confidence interval, 16.122–30.020; P < 0.001). The COVID-19 incidence rate in the Korean military was lower than that in the civilians, but after the emergence of the omicron variant, the increased incidence rate in the military followed that of the civilian population. Conclusion The outbreak of the omicron variant occurred in the Korean military despite maintaining high vaccination coverage and intensive non-pharmacological interventions.

Methemoglobin is a structurally modified form of hemoglobin incapable of binding oxygen, and elevated levels of methemoglobin cause tissue hypoxia. Occupational exposure to 2,4,6-trinitrotoluene, commonly called trinitrotoluene (TNT), causes methemoglobinemia. This case report describes a 27-year-old male sergeant who developed methemoglobinemia upon exposure to TNT after a blast injury while welding the walls of tank shells. This is the first case of its kind in the Republic of Korea. The patient had multiple burns in his abdomen and open fractures in his right leg. While his body temperature, heart rate, respiratory rate, arterial blood pressure, and chest X-ray were normal, arterial gas analysis revealed acute (methemoglobinemia concentration, 13.5%; oxygen saturation, 92.0%), probably caused by nitroglycerin exposure. Aspiration and adsorption through the skin and respiratory system were suspected to be the routes of entry. His methemoglobinemia normalized after 4 days after treating the wounds surgically, administering oxygen therapy, and performing blood transfusion.

Blast injuries are divided into four classes, and inhalation injuries are a quaternary class of blast injuries. An inhalation injury can be critical to the patient due to the possibility of related complications, such as airway obstruction resulting from upper airway edema and pneumonia. Once diagnosed, an inhalation injury should be treated with early intubation, aerosol therapy, and antibiotics as soon as possible. We should suspect this injury in circumstances involving fire and especially bomb attacks in a military setting. Antipersonnel landmines designed to damage the soldier by amputating the leg can cause blast injuries, but their power is limited to the lower extremity. However, we found an inhalation injury in a victim whose leg had been amputated by an antipersonnel landmine. As soon as we suspected an inhalation injury, we intubated the patient to preserve his airway and started acetylcysteine/heparin aerosol therapy. The patient also was treated with proper antibiotics for right lower lung pneumonia that developed as a sequela of inhalation injury. We could extubate the patient without any complications such as airway obstruction on the third day of intensive care, after which the patient was transferred to the general ward for active rehabilitation. This report presents the first known case of inhalation injury due to a landmine explosion.