In September 2012, the World Health Organization reported the first cases of pneumonia caused by the novel Middle East respiratory syndrome coronavirus (MERS-CoV). We describe a cluster of health care–acquired MERS-CoV infections. Medical records were reviewed for clinical and demographic information and determination of potential contacts and exposures. Case patients and contacts were interviewed. The incubation period and serial interval (the time between the successive onset of symptoms in a chain of transmission) were estimated. Viral RNA was sequenced. Between April 1 and May 23, 2013, a total of 23 cases of MERS-CoV infection were reported in the eastern province of Saudi Arabia. Symptoms included fever in 20 patients (87%), cough in 20 (87%), shortness of breath in 11 (48%), and gastrointestinal symptoms in 8 (35%); 20 patients (87%) presented with abnormal chest radiographs. As of June 12, a total of 15 patients (65%) had died, 6 (26%) had recovered, and 2 (9%) remained hospitalized. The median incubation period was 5.2 days (95% confidence interval [CI], 1.9 to 14.7), and the serial interval was 7.6 days (95% CI, 2.5 to 23.1). A total of 21 of the 23 cases were acquired by person-to-person transmission in hemodialysis units, intensive care units, or in-patient units in three different health care facilities. Sequencing data from four isolates revealed a single monophyletic clade. Among 217 household contacts and more than 200 health care worker contacts whom we identified, MERS-CoV infection developed in 5 family members (3 with laboratory-confirmed cases) and in 2 health care workers (both with laboratory-confirmed cases). Person-to-person transmission of MERS-CoV can occur in health care settings and may be associated with considerable morbidity. Surveillance and infection-control measures are critical to a global public health response.

To report the experience with Middle East respiratory syndrome coronavirus (MERS-CoV) infection at a single center in Saudi Arabia. Cases of laboratory-confirmed MERS-CoV occurring from October 1, 2012 to May 31, 2014 were reviewed retrospectively. Information sources included medical files, infection control outbreak investigations, and the preventive medicine database of MERS-CoV-infected patients. Data were collected on clinical and epidemiological aspects and outcomes. Seventy consecutive patients were included. Patients were mostly of older age (median 62 years), male (46, 65.7%), and had healthcare acquisition of infection (39, 55.7%). Fever (43, 61.4%), dyspnea (42, 60%), and cough (38, 54.3%) were the most common symptoms. The majority developed pneumonia (63, 90%) and required intensive care (49, 70%). Infection commonly occurred in clusters. Independent risk factors for severe infection requiring intensive care included concomitant infections (odds ratio (OR) 14.13, 95% confidence interval (CI) 1.58-126.09; p=0.018) and low albumin (OR 6.31, 95% CI 1.24-31.90; p=0.026). Mortality was high (42, 60%), and age ≥65 years was associated with increased mortality (OR 4.39, 95% CI 2.13-9.05; p<0.001). MERS-CoV can cause severe infection requiring intensive care and has a high mortality. Concomitant infections and low albumin were found to be predictors of severe infection, while age ≥65 years was the only predictor of increased mortality.

A human coronavirus, called the Middle East respiratory syndrome coronavirus (MERS-CoV), was first identified in September 2012 in samples obtained from a Saudi Arabian businessman who died from acute respiratory failure. Since then, 49 cases of infections caused by MERS-CoV (previously called a novel coronavirus) with 26 deaths have been reported to date. In this report, we describe a family case cluster of MERS-CoV infection, including the clinical presentation, treatment outcomes, and household relationships of three young men who became ill with MERS-CoV infection after the hospitalization of an elderly male relative, who died of the disease. Twenty-four other family members living in the same household and 124 attending staff members at the hospitals did not become ill. MERS-CoV infection may cause a spectrum of clinical illness. Although an animal reservoir is suspected, none has been discovered. Meanwhile, global concern rests on the ability of MERS-CoV to cause major illness in close contacts of patients.

No specific drugs or vaccines are available, and health systems are overburdened everywhere. We have to rely on targeted, non-coercive, community interventions with sufficient transparency and public engagement and trust, and implement them urgently (box 1).9 10 11 Such measures may help delay the exponential spread of the outbreak until drugs become available. Transparency and trust are critical to preserving a calm and compliant response to mitigation advice among the public.