Detection of Severe Acute Respiratory Syndrome Coronavirus 2 RNA on Surfaces in Quarantine Rooms

We investigated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) environmental contamination in 2 rooms of a quarantine hotel after 2 presymptomatic persons who stayed there were laboratory-confirmed as having coronavirus disease. We detected SARS-CoV-2 RNA on 8 (36%) of 22 surfaces, as well as on the pillow cover, sheet, and duvet cover.

We investigated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) environmental contamination in 2 rooms of a quarantine hotel after 2 presymptomatic persons who stayed there were laboratory-confirmed as having coronavirus disease. We detected SARS-CoV-2 RNA on 8 (36%) of 22 surfaces, as well as on the pillow cover, sheet, and duvet cover.
hospitalization, and her computed tomography images showed ground-glass opacities.
Approximately 3 hours after the 2 patients were identified as positive for SARS-CoV-2 RNA, we sampled the environmental surfaces of the 2 rooms in the centralized quarantine hotel in which they had stayed. Because of the SARS-CoV-2 outbreak in China, the hotel had been closed during January 24-March 18, 2020. Therefore, only these 2 persons had stayed in the rooms. We used a sterile polyester-tipped applicator, premoistened in viral transport medium, to sample the surfaces of the door handle, light switch, faucet handle, thermometer, television remote, pillow cover, duvet cover, sheet, towel, bathroom door handle, and toilet seat and flushing button. We also collected control swab samples from 1 unoccupied room. We collected each sample by swabbing each individual surface. We tested the samples with an rRT-PCR test kit (DAAN GENE Ltd, http://www.daangene.com) targeting the open reading frame 1ab (ORF1ab) and N genes of SARS-CoV-2. We interpreted cycle threshold (C t ) <40 as positive for SARS-CoV-2 RNA and C t >40 as negative.
We collected a total of 22 samples from the 2 rooms of the quarantine hotel ( Table 2). Eight (36%) samples were positive for SARS-CoV-2 RNA. C t values ranged from 28.75 to 37.59 (median 35.64). Six (55%) of 11 samples collected from the room of patient A were positive for SARS-CoV-2 RNA. Surface samples collected from the sheet, duvet cover, pillow cover, and towel tested positive for SARS-CoV-2 RNA, and surface samples collected from the pillow cover and sheet had a high viral load; C t for ORF1ab gene from the pillow cover was 28.97 and from the sheet, 30.58. Moreover, the C t values of these 2 samples correlated with those of patient A's nasopharyngeal (24.73) and fecal (33.12) swab samples at hospital admission. One surface sample from the faucet in patient B's room was positive for SARS-CoV-2 RNA; the C t was 28.75 for the ORF1ab gene. Again, we detected SARS-CoV-2 RNA from the surface samples of the pillow cover; C t was 34.57. All control swab samples were negative for SARS-CoV-2 RNA.

Conclusions
Our study demonstrates extensive environmental contamination of SARS-CoV-2 RNA in a relatively short time (<24 hours) in occupied rooms of 2 persons who were presymptomatic. We also detected SARS-CoV-2 RNA in the surface swab samples of the pillow cover, duvet cover, and sheet.
Evidence for SARS-CoV-2 transmission by indirect contact was identified in a cluster of infections at a shopping mall in China (10). However, no clear evidence of infection caused by contact with the contaminated environment was found. SARS-CoV-2 RNA has been detected on environmental surfaces in isolation rooms where the symptomatic or paucisymptomatic patients stayed for several days (3)(4)(5). In our study, we demonstrate high viral load shedding in presymptomatic patients, which is consistent with previous studies (8,9), providing further evidence for the presymptomatic transmission of the virus (5,11-15).  In addition, presymptomatic patients with high viral load shedding can easily contaminate the environment in a short period.
Our results also indicate a higher viral load detected after prolonged contact with sheets and pillow covers than with intermittent contact with the door handle and light switch. The detection of SARS-CoV-2 RNA in the surface samples of the sheet, duvet cover, and pillow cover highlights the importance of proper handling procedures when changing or laundering used linens of SARS-CoV-2 patients. Thus, to minimize the possibility of dispersing virus through the air, we recommend that used linens not be shaken upon removal and that laundered items be thoroughly cleaned and dried to prevent additional spread.
The absence of viral isolation in our investigation was an obstacle to demonstrating the infectivity of the virus, but SARS-CoV-2 has been reported to remain viable on surfaces of plastic and stainless steel for up to 4-7 days (6,7) and 1 day for treated cloth (7). In summary, our study demonstrates that presymptomatic patients have high viral load shedding and can easily contaminate environments. Our data also reaffirm the potential role of surface contamination in the transmission of SARS-CoV-2 and the importance of strict surface hygiene practices, including regarding linens of SARS-CoV-2 patients.