BackgroundFrom May to July 2015, the Republic of Korea experienced the largest outbreak of Middle East respiratory syndrome (MERS) outside the Arabian Peninsula. A total of 186 patients, including 36 deaths, had been diagnosed with MERS-coronavirus (MERS-CoV) infection as of September 30th, 2015.Materials and MethodsWe obtained information of patients who were confirmed to have MERS-CoV infection. MERS-CoV infection was diagnosed using real-time reverse-transcriptase polymerase chain reaction assay.ResultsThe median age of the patients was 55 years (range, 16 to 86). A total of 55.4% of the patients had one or more coexisting medical conditions. The most common symptom was fever (95.2%). At admission, leukopenia (42.6%), thrombocytopenia (46.6%), and elevation of aspartate aminotransferase (42.7%) were observed. Pneumonia was detected in 68.3% of patients at admission and developed in 80.8% during the disease course. Antiviral agents were used for 74.7% of patients. Mechanical ventilation, extracorporeal membrane oxygenation, and convalescent serum were employed for 24.5%, 7.1%, and 3.8% of patients, respectively. Older age, presence of coexisting medical conditions including diabetes or chronic lung disease, presence of dyspnea, hypotension, and leukocytosis at admission, and the use of mechanical ventilation were revealed to be independent predictors of death.ConclusionThe clinical features of MERS-CoV infection in the Republic of Korea were similar to those of previous outbreaks in the Middle East. However, the overall mortality rate (20.4%) was lower than that in previous reports. Enhanced surveillance and active management of patients during the outbreak may have resulted in improved outcomes.

Our findings show an association between the early CD8+ T cell response and the severity of the infection, and also provide basic information that may help to prepare effective control strategies for MERS in humans.

This nationwide, prospective cohort study evaluated pulmonary function and radiological sequelae according to infection severity in 73 survivors from the 2015 Middle East respiratory syndrome (MERS) outbreak in Korea. Patients with severe pneumonia in MERS-coronavirus infection had more impaired pulmonary function than those with no or mild pneumonia at the 1-year follow-up, which was compatible with the radiological sequelae. Severe pneumonia significantly impairs pulmonary function and makes long radiological sequelae in MERS.

BackgroundIn 2015, the largest outbreak of Middle East respiratory syndrome coronavirus (MERS-CoV) infection outside the Middle East occurred in South Korea. We summarized the epidemiological, clinical, and laboratory findings of the first Korean case of MERS-CoV and analyzed whole-genome sequences of MERS-CoV derived from the patient.Case presentationA 68-year-old man developed fever and myalgia 7 days after returning to Korea, following a 10-day trip to the Middle East. Before diagnosis, he visited 4 hospitals, potentially resulting in secondary transmission to 28 patients. On admission to the National Medical Center (day 9, post-onset of clinical illness), he presented with drowsiness, hypoxia, and multiple patchy infiltrations on the chest radiograph. He was intubated (day 12) because of progressive acute respiratory distress syndrome (ARDS) and INF-α2a and ribavirin treatment was commenced. The treatment course was prolonged by superimposed ventilator associated pneumonia. MERS-CoV PCR results converted to negative from day 47 and the patient was discharged (day 137), following rehabilitation therapy. The complete genome sequence obtained from a sputum sample (taken on day 11) showed the highest sequence similarity (99.59%) with the virus from an outbreak in Riyadh, Saudi Arabia, in February 2015.ConclusionsThe first case of MERS-CoV infection had high transmissibility and was associated with a severe clinical course. The patient made a successful recovery after early treatment with antiviral agents and adequate supportive care. This first case in South Korea became a super-spreader because of improper infection control measures, rather than variations of the virus.

We evaluated the diagnostic and clinical usefulness of blood specimens to detect Middle East respiratory syndrome coronavirus infection in 21 patients from the 2015 outbreak in South Korea. Viral RNA was detected in blood from 33% of patients at initial diagnosis, and the detection preceded a worse clinical course.