Extensive Viable Middle East Respiratory Syndrome (MERS) Coronavirus Contamination in Air and Surrounding Environment in MERS Isolation Wards

Abstract

Background: The largest outbreak of Middle East respiratory syndrome coronavirus (MERS-CoV) outside the Middle East occurred in South Korea in 2015 and resulted in 186 laboratory-confirmed infections, including 36 (19%) deaths. Some hospitals were considered epicenters of infection and voluntarily shut down most of their operations after nearly half of all transmissions occurred in hospital settings. However, the ways that MERS-CoV is transmitted in healthcare settings are not well defined.

Methods: We explored the possible contribution of contaminated hospital air and surfaces to MERS transmission by collecting air and swabbing environmental surfaces in 2 hospitals treating MERS-CoV patients. The samples were tested by viral culture with reverse transcription polymerase chain reaction (RT-PCR) and immunofluorescence assay (IFA) using MERS-CoV Spike antibody, and electron microscopy (EM).

Results: The presence of MERS-CoV was confirmed by RT-PCR of viral cultures of 4 of 7 air samples from 2 patients' rooms, 1 patient's restroom, and 1 common corridor. In addition, MERS-CoV was detected in 15 of 68 surface swabs by viral cultures. IFA on the cultures of the air and swab samples revealed the presence of MERS-CoV. EM images also revealed intact particles of MERS-CoV in viral cultures of the air and swab samples.

Conclusions: These data provide experimental evidence for extensive viable MERS-CoV contamination of the air and surrounding materials in MERS outbreak units. Thus, our findings call for epidemiologic investigation of the possible scenarios for contact and airborne transmission, and raise concern regarding the adequacy of current infection control procedures.

Keywords: MERS; contamination; transmission.

Figure 1.

A , Floor plan of the well-equipped Middle East respiratory syndrome–designated hospital where each negative-pressure room had an anteroom and postroom. The “x” and slash (/) indicate the air supply and air exhaust, respectively. Patient 1 was a 69-year-old man with pneumonia who received mechanical ventilation and extracorporeal membrane oxygenation on day 22 from the onset of symptoms. B , Results of viral culture of air and swabs from patient 1's room. Patient 2 was a 54-year-old man with pneumonia who received mechanical ventilation on day 16 from the onset of symptoms. C , Results of viral cultures of air and swabs from patient 2's room. The solid blue lines radiating from the large blue ovals indicate the angles of observation used for drawing the illustrations of the patients’ rooms.

Figure 2.

A , Floor plan of the Middle East respiratory syndrome (MERS)–designated hospital that was switched to isolation wards in the MERS outbreaks where each room had a portable negative-pressure device and no anteroom and shared a common corridor. The “x” and slash (/) indicate air supply and air exhaust, respectively. Patient 3 was a 54-year-old man with pneumonia who received mechanical ventilation on day 19 from the onset of symptoms. B , Results of viral culture of air and swabs from patient 3's room. The solid blue lines radiating from the large blue oval indicate the angle of observation used to draw the illustration of the patient's room.