Detection of SARS-CoV-2 RNA on Surfaces in Quarantine Rooms

In This Article

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.^[3–5] 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.

This work was supported by the National Major Project for Control and Prevention of Infectious Disease of China (2017ZX10303401-006), the National Natural Science Foundation of China (81773494 and 81621005), and the Special National Project on investigation of basic resources of China (2019FY101502).

Table 1. Timeline from return to China by 2 persons with presymptomatic SARS-CoV-2 infection to results of environmental sampling of their rooms at a centralized quarantine hotel, 2020*
Characteristic	Patient A	Patient B
Date returned to China	19 Mar	20 Mar
Date entered quarantine	19 Mar	21 Mar
Date of SARS-CoV-2 RNA–positive detection	20 Mar	22 Mar
Date of environmental surface sampling	20 Mar	22 Mar
Symptoms at hospital admission	None	None
C_t for clinical samples at admission†
Nasopharyngeal swab	24.72	27.87
Sputum	28.61	23.23
Fecal swab	33.12	NA
Symptoms during hospitalization	Fever, chills, cough	Fever, cough, sputum, sore throat
Disease severity	Mild	Moderate

*C_t, cycle threshold; NA, not available; rRT-PCR, real-time reverse transcription PCR; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.
†A lower C_t indicates a higher viral load. Only C_t values for open reading frame1ab (ORFab1) gene of SARS-CoV-2 were provided in the table because the Ct values for nucleoprotein were similar to values of ORFab1.

Table 2. Results of environmental sampling of 2 rooms at a centralized quarantine hotel occupied by 2 presymptomatic SARS-CoV-2–infected patients, China, 2020*
Environmental source†	Values‡
Environmental source†	Patient A's room	Patient B's room
Door handle	0/1	0/1
Light switch	1/1 (37.59)	0/1
Faucet	0/1	1/1 (28.75)
Bathroom door handle	1/1 (36.02)	0/1
Toilet seat, flush handle	0/1	0/1
Thermometer	0/1	0/1
TV remote	0/1	0/1
Pillow cover	1/1 (28.98)	1/1 (34.57)
Duvet cover	1/1 (35.64)	0/1
Sheet	1/1 (30.58)	0/1
Towel	1/1 (36.98)	0/1
Total, no. (%)	6/11 (54.5)	2/11 (18.2)

*Values are no. positive/total (C_t) except as indicated. C_t, cycle threshold; rRT-PCR, real-time reverse transcription PCR; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.
†One swab was taken from each site except the light switch, from which 2 swabs were taken.
‡All samples taken from patients A and B after disinfection were negative and not included in this table. A lower C_t indicates a higher viral load. Only C_t values for open reading frame 1ab (ORFab1) gene of SARS-CoV-2 were provided because the C_t values for nucleoprotein were similar to those of ORFab1.