Viral Shedding and Environmental Cleaning in Middle East Respiratory Syndrome Coronavirus Infection

Song, Joon Young; Cheong, Hee Jin; Choi, Min Joo; Jeon, Ji Ho; Kang, Seong Hee; Jeong, Eun Ju; Yoon, Jin Gu; Lee, Saem Na; Kim, Sung Ran; Noh, Ji Yun; Kim, Woo Joo

During the hospitalization of both patients, environmental cleaning was conducted twice a day; bottom of each room was wiped with bleach solution (1:100 dilution of 5% sodium hypochlorite), but other surfaces were cleaned with 70% alcohol-based disinfectants. Environmental surveillance was conducted after discharge of patients. Environmental specimens were collected from 12 sites of negative-pressure isolation room and anteroom at each time point: right after discharge (H0), 2 hours from room cleaning (H2), 24 hours from room cleaning (H24) and 48 hours from room cleaning (H48) ( Table 2 ). After discharge in case 1, each environmental surface was wiped with diluted sodium hypochlorite, but monitors were T20 T22 T24 T26 T28 T31 T32 T33 T4 T15 T17 T19 T21 T23 T26 T27 cleaned with 70% alcohol-based disinfectants. As for patient 2, all surfaces including monitor were wiped with diluted sodium hypochlorite. As presented in Table 2 , environmental RT-PCR was weakly positive for bed guardrail and monitors in case of patient 1. Even after cleaning the monitors with 70% alcohol-based disinfectant, RT-PCR was still weakly positive, which might suggest an inadequate environmental cleaning. RT-PCR was converted to negative only after wiping with diluted sodium chlorite. As for case 2, RT-PCR was weakly positive for anteroom wall initially, but MERS-CoV RNA was not detected anywhere after cleaning with diluted sodium chlorite. This study shows that viral shedding persists for 2-4 weeks in patients with MERS-CoV pneumonia, contaminating the surrounding environments. As previously reported, MERS-CoV can survive more than 48 hours at the environmental surfaces, so appropriate cleaning and strict contact precaution would be required [5] . It is not clear how intra-hospital spread occurred efficiently, but contaminated fomites might have played an important role. Unfortunately, during Korean MERS outbreak in June 2015, specimen was not collected from healthcare worker's gown, stethoscopes and other devices in common. Such an investigation is required to clarify the fomite-mediated MERS-CoV transmission.