Since 2012, the Middle East respiratory syndrome coronavirus (MERS-CoV) has infected almost 300 people, many of them healthcare workers including nurses and doctors. Infections of health care workers and patients that take place within or are associated with a hospital or health care facility are referred to as nosocomial infections. A large number of MERS cases can be classified as nosocomial infections. For the purposes of this discussion, localized geographic clusters of MERS-CoV cases that appear to represent hospital-acquired infections are referred to as nosocomial MERS clusters. Under this definition, there has been at least 10 separate nosocomial clusters of MERS cases.
Of these clusters, only two have been reported in the literature [1,2]. The remaining nosocomial clusters are identified based on media reports, ministry of health reports, and World Health Organization reports. The quality of this data is uncertain but trends are clear and speculations can be advanced.
The table below identifies these nosocomial clusters by location, month of outbreak for the cluster, the putative number of MERS cases within the cluster, and the number of infected health care workers reportedly associated with the cluster. The case counts include both confirmed and suspected/probable cases. The map below depicts the general locations of these clusters throughout the Arabian Peninsula.
Health care workers represent about 44% of the nosocomial cluster cases. In addition to the health care workers included in the clusters, another 21 health care workers are reported as sporadic or isolated MERS cases. The source of infection for these other health care workers is not identified, but it is likely that there have been additional nosocomial clusters that are not reported.
Based on these data, it is clear that infection of healthcare workers with the MERS coronavirus is not a rare or random event. More than 2 years after initial hospital cluster in Jordan, health care workers continue to become infected while treating patients. We can assume that health care workers in the Arabian Peninsula region, are now familiar with, and aware of, the dangers of MERS. The fact that MERS is still infecting health care workers and possibly other patients within a hospital setting strongly suggests that MERS is highly infectious among individuals who have close contact with each other. The fact that about 25% of all reported MERS infections are doctors, nurses, and other health care workers is indicative of the infectious nature of this novel coronavirus.
 Novel coronavirus infections in Jordan, April 2012: epidemiological findings from a retrospective investigation