Middle East Respiratory Syndrome (MERS)

The emergence of the beta coronavirus that causes Middle East Respiratory Syndrome (MERS), a viral, often fatal, respiratory illness in humans, was first reported in the Kingdom of Saudi Arabia in 2012, according to various studies.

The MERS novel coronavirus (CoV), MERS-CoV causes more severe disease in people with underlying chronic medical conditions such as diabetes mellitus, renal failure, chronic lung disease, and compromised immune systems, says the WHO. 

The mortality rate for people infected with the MERS-CoV virus is approximately 30%. However, research indicates this may be an overestimate, as mild cases may be missed by existing surveillance systems.

The demographic and epidemiological characteristics of MERS-CoV reported cases when compared with the same corresponding periods in 2014–2020, do not show any significant difference or change. The number of cases reported in this period was less than all other corresponding periods.

The male age group 50–59 years continues to be at the highest risk for acquiring MERS-CoV infection as primary cases, says the WHO.

MERS-CoV Cases During 2020

  • Saudi Arabia's Ministry of Health (MOH) has reported 2 more MERS-CoV cases, one in Riyadh and the other in Mecca, raising the number reported in March 2020 to eight.
  • At the end of January 2020, the WHO reported a total of 2,519 laboratory-confirmed cases of MERS, including 866 associated deaths (case-fatality rate: 34.3%) were reported globally. The majority of these cases were reported from Saudi Arabia (2,121 cases), including 788 related deaths, which is a case-fatality rate of 37.1%.
  • So far this year, 9 of 13 regions of Saudi Arabia reported cases and of these, Eastern Province, Hail, Makkah, Najran, and Riyadh have reported the most cases.
  • On February 18, 2020, Qatar reported another case of MERS-CoV. All contacts of the patient tested negative for MERS-CoV. Since 2012, including this case, Qatar has reported 23 human cases of MERS-CoV. 

MERS-CoV Risk Assessment

MERS-CoV History

  • From 2012 until January 31, 2020, the total number of laboratory-confirmed MERS-CoV infection cases reported globally to WHO is 2,519 with 866 associated fatalities, from 27 different countries. The vast majority of these MERS-CoV cases were confirmed in Saudi Arabia. 
  • Only 2 patients in the USA have ever tested positive for MERS-CoV infection—both in May 2014—while more than 1,300 people have tested negative. 

MERS-CoV Transmission

  • Humans are infected with MERS-CoV from direct or indirect contact with dromedaries. People should avoid drinking raw camel milk or camel urine or eating meat that has not been properly cooked.
  • MERS-CoV has demonstrated the ability to transmit between humans.
  • MERS-CoV appears to cause more severe disease in people with diabetes, renal failure, chronic lung disease, and immunocompromised persons. Therefore, these people should avoid close contact with animals, particularly dromedaries, when visiting farms, markets, or barn areas where the virus is known to be potentially circulating.

MERS-CoV Symptoms

  • Most people infected with MERS-CoV developed severe respiratory illness, including fever, cough, shortness of breath, and can be very fatal, says the CDC.
  • The median time from illness onset to hospitalization is approximately 4 days.
  • In critically ill patients, the median time from onset to intensive care unit admission was approximately 5 days.
  • Moreover, the median time from onset to death is approximately 12 days, says the CDC.

MERS-CoV Vaccine Candidates

  • ChAdOx1 MERS-CoV is a vaccine candidate that consists of the replication-deficient simian adenovirus vector ChAdOx1, containing the MERS Spike protein antigen. This phase 1b study is assessing the safety and immunogenicity of the ChAdOx1 MERS vaccine in healthy Middle Eastern adult volunteers aged 18-50.
  • INO-4700 MERS-CoV is a DNA plasmid vaccine that expresses the MERS CoV spike (S) glycoprotein. Inovio expects to advance INO-4700 into a Phase 2 field study in the Middle East and Africa where outbreaks have been observed.
  • MVA MERS (Modified Vaccinia virus Ankara) is a vaccine candidate that contains the full-length spike gene of MERS-CoV. In this phase I, first-in-human clinical trial, healthy volunteers in two different dose cohorts will be vaccinated twice with the candidate vaccine MVA-MERS-S. 

MERS-CoV Treatments

  • A MERS therapy study published on January 10, 2020, found that remdesivir and interferon had superior antiviral activity when compared to lopinavir and ritonavir. In transgenic mice, both prophylactic and therapeutic doses of remdesivir improved lung function and reduced lung viral loads and severe pathology. These researchers also found that the prophylactic combination therapy slightly reduced viral loads without affecting other disease measures and that therapeutic combo therapy improved lung function but didn't reduce virus replication in severe disease. The team said the findings were similar to their earlier studies on remdesivir and severe acute respiratory syndrome coronavirus (SARS) and show evidence of the potential to treat MERS-CoV.

MERS-CoV Tests

  • MERS-CoV testing version 2.1 was last updated by the CDC on August 2, 2019, which says, before collecting and handling specimens for MERS-CoV, determine whether the person meets the current definition for a “patient under investigation” (PUI). 
  • To increase the likelihood of detecting infection, the CDC recommends collecting multiple specimens from different sites at different times after symptom onset, if possible. The laboratory must follow the protocol for the CDC rRT-PCR assay, in the USA.


NOTE: The content on this page is sourced from the CDC, WHO,, and the Precision Vax network of websites. This information was last fact-checked by healthcare providers, such as Dr. Robert Carlson, on March 28, 2020.