WHO

Between 2012 and 30 June 2018, 2229 laboratory confirmed cases of Middle East respiratory syndrome coronavirus (MERS-CoV) infection were reported to WHO, 83% of whom were reported by the Kingdom of Saudi Arabia (Figure 1). In total, cases have been reported from 27 countries in the Middle East, North Africa, Europe, the United States of America, and Asia (Table 1). Males above the age of 60 with an underlying medical conditions, such as diabetes, hypertension and renal failure, are at a higher risk of severe disease, including death. To date, 791 individuals have died (crude CFR 35.5%).

Since the last global update published on 21 July 2017, 189 laboratory-confirmed cases of MERS-CoV from four countries were reported to WHO (182 from Saudi Arabia, three from Oman, three from the United Arab Emirates, and one from Malaysia), of whom 60 (31.7%) have died. Among these cases, 75.5% were male and the median age was 54 years old (IQR 40-65.5; range 10-93 years old). The median age is similar to the median age of all cases reported to WHO since 2012 (52 years old, IQR 37-65).
At the time of writing, 19 of 189 (10.0%) patients were reported as asymptomatic or having mild. At least one underlying condition was reported in 137 cases (72%) since the last update, including chronic renal failure, heart disease, diabetes mellitus, and hypertension.
Overall, the epidemiology, transmission patterns, clinical presentation of MERS patients and viral characteristics reported since the last update are consistent with past patterns described in previous WHO risk assessments: MERS-CoV is a zoonotic virus that has repeatedly entered the human population via direct or indirect contact with infected dromedary camels in the Arabian Peninsula. Limited, non-sustained human-to-human transmission mainly in health care settings continues to occur, primarily in Saudi Arabia. The risk of exported cases to areas outside of the Middle East due to travel remains significant.
While there have been significant improvements in surveillance for MERS, especially in the Middle East, and in reacting to suspect clusters, early identification in the community and in health care systems, compliance with the infection prevention and control measures and contact follow up remain major challenges for MERS outbreak prevention and control.

The continued importance of MERS-CoV in health care settings
Since the last global update of 21 July 2017, 17 of the 45 secondary cases reported to WHO were associated with transmission in a health care facility. These cases included health care workers (12 cases), patients sharing rooms/wards with MERS patients, or family visitors.
Though not unexpected, these transmission events continue to be deeply concerning, given that MERS-CoV is still a relatively rare disease about which medical personnel in health care facilities have low awareness. Globally, awareness for MERS is low and, because symptoms of MERS-CoV infection are non-specific, initial cases are sometimes easily missed. With improved compliance in infection prevention and control, namely adherence to the standard precautions at all times, human-to-human transmission in health care facilities can be reduced and possibly eliminated with additional use of transmissionbased precautions.
Since the last update of July 2017, several MERS clusters were reported, including the following:
 In July-August 2017, two clusters of MERS were reported from AL-Jawf Region, Saudi Arabia. These clusters were not epidemiologically linked.
 The first health care associated cluster included 13 cases, 2 who died. Among the 12 secondary cases, 10 were asymptomatic, including 8 health care workers.
 The second cluster included 7 cases, 6 of whom were household contacts. Of the 6 secondary cases, five were asymptomatic. None of the cases identified in this cluster were health care workers and there were no fatalities.
 In January-February 2018, a health care associated cluster was reported in Hafr Al Batin Region, Saudi Arabia. The cluster included 4 cases and 1 death, including 3 asymptomatic health care workers identified through contact tracing.
 In February-March 2018, a health care associated cluster of 6 cases occurred in a hospital in Riyadh, Saudi Arabia. Of the 6 cases, none were health care workers and three were fatal.
 In March 2018, there was a household cluster reported from Jeddah, Saudi Arabia. This cluster included 3 individuals, all of whom survived.

In May-June 2018, a household cluster was reported from the Najran Region, Saudi Arabia. The index case reported regular contact with dromedary camels. Ten family contacts and one health care worker were identified as secondary cases. Out of the 12 cases identified in this cluster, none were fatal.
Since 2015, the increase in the number of asymptomatic contacts identified in health care settings is due to a policy change by the Ministry of Health of the Kingdom of Saudi Arabia, in which all high-risk contacts are tested for MERSCoV regardless of the development of symptoms. This comprehensive contact identification, follow-up, testing and isolation of positive cases continues into 2018.
Drivers of transmission and the exact modes of transmission in health care settings still are unclear and are currently the focus of collaborative scientific research. From observational studies, transmission in health care settings is believed to have occurred before adequate infection prevention and control procedures were applied and cases were isolated. Investigations at the time of the outbreaks indicate that aerosolizing procedures conducted in crowded emergency departments or medical wards with sub-optimal infection prevention and control measures in place resulted in human-to-human transmission and environmental contamination.
Community-acquired cases and reported links to dromedary camels
Since the last update, 56 human cases are believed to have been infected in the community. Of these 56 reported cases, 37 (66.1%) reported direct or indirect contact with dromedaries in Saudi Arabia (33 cases), Oman (2 cases), the United Arab Emirates (one case) and Malaysia (one case; contact with dromedary was in Saudi Arabia).
Improvement in multi-sectoral investigation of community-acquired cases is evident, including testing of dromedary animals/herds in the vicinity of community-acquired laboratory-confirmed cases and follow-up of human contacts of laboratory-confirmed cases. The Ministries of Health in affected countries notify the Ministries of Agriculture when human cases report a link with animals. Investigations in animals are carried out by officials from the Ministries of Agriculture and results, if positive for MERS-CoV, are reported to OIE.
Exported cases identified outside the Middle East Since the last update, one case was reported outside of the Middle East. The case, a 55 year old, had recently returned from Jeddah to Malaysia in December 2017. The patient was treated and recovered, contacts were identified and followed and no further cases were identified by authorities in Malaysia.

Summary – information available from 2012 to date
Thus far, no sustained human-to-human transmission has occurred anywhere in the world, however limited non-sustained human-to-human transmission in health care facilities remains a prominent feature of this virus. WHO continues to work with health authorities in the affected countries to prevent and minimize health care-associated cases. WHO understands that health authorities in affected countries, especially those in the most affected countries, are aggressively investigating cases and contacts, including testing for MERS-CoV among asymptomatic contacts, and applying mitigation measures to stop human-to-human transmission in health care settings. These efforts are proving successful in mitigating the size of outbreaks.

Of all laboratory-confirmed cases reported to date (n=2228), the median age is 52 (IQR 37-65) and 67.2% are male.
At the time of reporting, 21% of the 2228 cases were reported to have no or mild symptoms, while 46% had severe disease or died. Overall, 18.6% of the cases reported to date are health care workers.

Since 2012, 27 countries have reported cases of MERS-CoV infection. In the Middle East: Bahrain, Egypt, Iran, Jordan, Kuwait, Lebanon, Oman, Qatar, Saudi Arabia, the United Arab Emirates and Yemen; in Africa: Algeria and Tunisia; in Europe: Austria, France, Germany, Greece, Italy, the Netherlands, Turkey and the United Kingdom; in Asia: China, the Republic of Korea, Malaysia, the Philippines and Thailand; and in the Americas: the United States of America (Table 1).
The majority of cases (approximately 83%) have been reported from Saudi Arabia (Figure 1).
Populations in close contact with dromedaries (e.g. farmers, abattoir workers, shepherds, dromedary owners) and health care workers caring for MERS-CoV patients are believed to be at higher risk of infection. Healthy adults infected with MERS-CoV tend to have mild subclinical or asymptomatic infections. To date, limited human-to-human transmission has occurred between close contacts of confirmed cases in household settings. More efficient human-to-human transmission occurs in health care settings due to inadequate and/or incomplete compliance with the infection prevention and control measures and delay in triage or isolation of suspected MERS patients. Health care-associated transmission has been documented in several countries between 2012-2016, including Saudi Arabia, Jordan, the United Arab Emirates, France, the United Kingdom, and the Republic of Korea with varying outbreak sizes (2-180 reported cases per outbreak). The largest outbreak outside of the Middle East occurred in the Republic of Korea resulting in 186 cases (including one case who travelled to China) and 39 deaths. Overall, the reproduction number (R0) of MERS-CoV is <1 with significant heterogeneity in specific contexts. Specifically, outbreaks in health care settings can have R>1, but they can be brought under control (R<1) with proper application of infection prevention and control measures and early isolation of subsequent cases.