Recently, the European Centre for Disease Prevention and Control (ECDC) produced a summary report on the status of the Middle East respiratory syndrome coronavirus (MERS-CoV) outbreak for the 130+ cases that have been reported since March 2012 .
While epidemiological data about these cases are presented in this report, several aspects of the report need further elaboration and discussion. As discussed on a USA Center for Disease Control web page  and noted in the ECDC report, human clusters are prevalent for this novel disease. At least 14 MERS-CoV clusters have been reported. Single clusters have been reported from several countries, France, Italy, Jordan, Tunisia, and the United Kingdom. And the Kingdom of Saudi Arabia, which has reported more than 100 MERS-CoV cases, has experienced at least seven cluster outbreaks in seven separate geographic areas.
The ECDC authors state
Information on geographic clusters of cases can provide important insight for public health officials into the mode of transmission, the transmissibility of the novel pathogen, and the potential identification of the non-human reservoir of a pathogen. What is not mentioned by the ECDC authors is that about 50% of all reported MERS-CoV cases have occurred in a cluster as defined by the World Health Organization (WHO) . What is also not mentioned by the ECDC authors is how the index cases in these clusters became infected. The non-human source of this coronavirus has yet to be identified.We identified 14 clusters of 2-34 cases, where the primary cases were identified or suspected. However, data quality on the clusters is weak. All of the known 14 primary cases in clusters were adult men (24-83 years old) who were most likely exposed on the Arabian Peninsula. Of 129 cases with available information on transmission, 33 (26 percent) were possible nosocomial transmissions, 15 of these cases were healthcare workers (HCW). 17 of the 23 cases reported as HCW were female.
Of greater concern is the fact that at least 33 cases may have resulted from nosocomial transmissions. Nosocomial infection is a result of pathogen transmission within a hospital or healthcare facility. This means that these 30+ individuals, including healthcare workers, contracted MERS-CoV in a healthcare facility such as a hospital. They did not contract the disease from an intermediate animal source. Infections within a healthcare facility are associated with human-to-human transmission.
Several reports indicate that at least nine of these nosocomial infections were hospital patients most likely with comorbidities. However, more alarming is that a number of healthcare workers were also infected in the hospital or healthcare treatment facility. This means that the coronavirus is transmissible not just among elderly individuals with chronic diseases but also among healthy younger healthcare workers who should be aware of, and prepared for, the dangers of human-to-human transmission.
The nature of the transmissibility of the MERS-CoV is not clear, but the fact that numerous clusters have been reported and that human-to-human transmission is occurring among both patients and healthcare workers in healthcare facilities is cause for serious concern and demonstrates a need for increased monitoring and surveillance for this novel disease.
 Interim surveillance recommendations for human infection with Middle East respiratory syndrome coronavirus