Although it has not been sustained in other countries following introductions and outbreaks, Middle East Respiratory Syndrome (MERS) coronavirus has established an endemic presence in the Kingdom of Saudi Arabia since it emerged in 2012, the World Health Organization (WHO) reports.1

As of June 30, 2019, there have been 2,449 laboratory-confirmed cases of MERS reported, with 84% in Saudi Arabia and the rest in 27 other countries, including the United States. There have been 845 MERS deaths, resulting in a mortality rate of 35%. MERS is a zoonotic virus that has established a reservoir in camels on the Arabian Peninsula.

“Limited, nonsustained, human-to-human transmission, mainly in healthcare settings, continues to occur, primarily in Saudi Arabia,” the WHO reported. “The risk of exported cases to areas outside of the Middle East due to travel remains significant.”

While there has been community transmission, MERS is a particular threat to spread in healthcare settings.

“[T]ransmission in healthcare settings is believed to have occurred before adequate infection prevention and control procedures were applied and cases were isolated,” WHO reported. “Investigations at the time of the outbreaks indicate that aerosolizing procedures conducted in crowded emergency departments or medical wards with suboptimal infection prevention and control measures in place resulted in human-to-human transmission and environmental contamination.”

Since the last WHO update on June 30, 2018, 52 of the 97 secondary cases reported were associated with transmission in healthcare facilities. These cases included 23 healthcare workers. Patient infections occurred in those sharing rooms or wards with MERS patients. Some visitors also were infected.

“Though not unexpected, these transmission events continue to be deeply concerning, given that MERS is still a relatively rare disease about which medical personnel in healthcare facilities have low awareness,” WHO concluded.

Global awareness of MERS generally is low, and cases may be missed due to nonspecific initial symptoms.

“With improved compliance in infection prevention and control, namely adherence to the standard precautions at all times, human-to-human transmission in healthcare facilities can be reduced and possibly eliminated with additional use of transmission-based precautions,” WHO noted.


  1. World Health Organization. MERS global summary and assessment of risk, July 2019. Available at: Accessed Aug. 9, 2019.