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Factors that contributed in prolongation of an outbreak of Middle East Respiratory Syndrome (MERS) in major hospital in Riyadh, Saudi Arabia.


MERS outbreaks since 2012 are causing burden to lives and resources in the kingdom. Health care facilities are the main environment for these outbreaks. From June-September, 2015 a cluster of MERS-CoV cases occurred in the Emergency rooms (ER) of a large hospital in Riyadh, Saudi Arabia. The factors acted in extending the outbreak in this health care facility were the scope of this study.


All RT-PCR confirmed MERS patients excluding health care workers were included as cases. From a list of 22,253 patients who visited ER during the outbreak period, 165 controls were selected at random. Paper and electronic records were used to study factors acted in extending the outbreak in this health care setting.


Total MERS cases were 130, primary cases (N=20) and secondary (N=67) all passed through ER except six secondary cases. The hospital ER composed of seven sections each has different number of beds and dedicated for certain patients according to the medical status. The mean (SD, range) of stay in ER in hours 167 (+ 146, 7-747), secondary cases stayed 2-3 times longer in ER in comparison to controls. The mean (SD) number of sections visited in ER by primary and secondary cases were 2.3 +1.4 (range 1-6), 2.9 +1.5 (range 1-7) respectively. Some sections of ER were associated more with MERS-CoV transmission. The mean number of changing the bed in ER for primary and secondary cases were 3.4+1.8, 3.89+2.1 respectively. The outbreak period was divided to three phases according to actions and level of infection control practices. Primary cases were almost even in the all three phases but the number of secondary infections reached the peak in phase two and decreased to almost zero in phase three.


Infection control practices played a core role in controlling the outbreak as showed in phase three of this outbreak even if the ER services not stopped. Keeping patients for long time in ER, their traffic between and within sections and late isolation of suspected cases added further risk. Aerosol generating procedures in ER contributed in exposing both HCWs and patients. Medium size hospital might be safer in regard to MERS outbreaks but this need father studies.