Risks of Death and Severe Disease in Patients With Middle East Respiratory Syndrome Coronavirus, 2012–2015

Caitlin M. Rivers; Maimuna S. Majumder; Eric T. Lofgren


Am J Epidemiol. 2016;184(6):460-464. 

In This Article

Abstract and Introduction


Middle East respiratory syndrome coronavirus (MERS-CoV) is an emerging pathogen, first recognized in 2012, with a high case fatality risk, no vaccine, and no treatment beyond supportive care. We estimated the relative risks of death and severe disease among MERS-CoV patients in the Middle East between 2012 and 2015 for several risk factors, using Poisson regression with robust variance and a bootstrap-based expectation maximization algorithm to handle extensive missing data. Increased age and underlying comorbidity were risk factors for both death and severe disease, while cases arising in Saudi Arabia were more likely to be severe. Cases occurring later in the emergence of MERS-CoV and among health-care workers were less serious. This study represents an attempt to estimate risk factors for an emerging infectious disease using open data and to address some of the uncertainty surrounding MERS-CoV epidemiology.


Middle East respiratory syndrome coronavirus (MERS-CoV) is a stage 3 zoonosis that has been reported in 26 countries, including the United States.[1,2] The virus was first recognized in Saudi Arabia in 2012, though it may have been circulating in the region much longer.[3,4] As of August 18, 2015, there have been 1,413 confirmed cases and 502 deaths.[5] The virus causes severe respiratory illness in humans and has a mortality rate of 30%–40%.[6] Treatment for MERS-CoV cases is limited to supportive care.

Certain groups may be at higher risk of contracting the virus or of having their cases ascertained due to illness severity, including males and those with comorbid medical conditions, such as diabetes and heart disease. Common symptoms include fever, cough, shortness of breath, chest pain, and diarrhea.[7,8] The virus is probably transmitted from camels to humans, and stuttering chains (groups of cases linked by a continuous chain of transmission events that arise periodically) of human-to-human transmission are also possible.[4,7–10] Human-to-human transmission occurs between 2 people in close contact, a circumstance common in households and health-care settings. Early identification and isolation of cases is critical for limiting spread of the virus.

Information on the epidemiology of MERS-CoV has been limited to date. Prior work on the 2013 influenza (A)H7N9 outbreak found that line listings of cases aggregated from publicly available sources like media and public health reports compare favorably to official line listings.[11] These public line listings can be used to gain insight into an ongoing outbreak in a timely manner, as official data tend to be released only after outbreaks are over. Real-time analyses are vital to planning and implementing effective public health control measures to prevent the spread of the disease. We used publicly available data to evaluate the risks of death and severe disease among patients with MERS-CoV.