Outbreak of Middle East Respiratory Syndrome in the Emergency Room of a Large Tertiary Hospital in Riyadh, Saudi Arabia, 2015: Lessons Learnt

Background: An outbreak of Middle East respiratory syndrome (MERS) occurred in the emergency room of a large tertiary hospital in Riyadh City, Saudi Arabia in 2015. This study describes the outbreak and the factors that led to its continuation. Methods: We collected epidemiological data for all laboratory-confirmed cases diagnosed at the hospital during the outbreak from hospital surveillance data and electronic and paper medical records of the patients visiting or admitted to the hospital. We calculated the incubation period, duration of stay in different emergency room units and hospital wards before and after the onset of symptoms, the time between admission and collection of biological specimens, receipt of laboratory tests and duration of virus shedding. Results: The outbreak continued for eight weeks, with 130 MERS cases, including 20 primary cases and 110 secondary cases, of which 43 were healthcare workers. There were 51 deaths (case fatality rate = 58.6%, 95% CI: 48.1 68.4). The incubation period was 7 days. The time between exposure to a known MERS case and onset of symptoms of MERS was constant throughout the outbreak: mean 6.3 7.5 days (range 2 12 days). Mean times between onset of symptoms and laboratory confirmation of MERS at the start of the outbreak were 23 (SD 9) days and 6 (SD 3.5) days for primary and secondary cases respectively. The mean (SD) duration of shedding of MERS-CoV was 23.7 (12.2) days, range 5.5 67.5 days. The mean (SD) length of stay in the emergency room was 167 (146) hours, range 7 747 hours. Three of seven emergency room units were associated with MERS-CoV infection: adult care expansion (OR = 26.0, 95% CI: 4.5 566), resuscitation (OR = 5.8, 95% CI: 2.1 18.3) and hydration (OR = 4.4, 95% CI: 1.4 16.5). Conclusion: This is the largest outbreak of MERS reported to date in a single health facility in Saudi Arabia. Contributory factors included prolonged stay of patients in an overcrowded emergency room, inadequate implementation of infection control and prevention measures, and delayed detection and reporting of MERS cases. Delays could have been reduced if a respiratory triaging system existed in the emergency room, healthcare workers had been better trained, infection prevention and control measures had been implemented, and test requests had been monitored.