Detection and infectivity potential of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) environmental contamination in isolation units and quarantine facilities

Abstract

Objectives: Environmental surfaces have been suggested as likely contributors in the transmission of COVID-19. This study assessed the infectivity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) contaminating surfaces and objects in two hospital isolation units and a quarantine hotel.

Methods: SARS-CoV-2 virus stability and infectivity on non-porous surfaces was tested under controlled laboratory conditions. Surface and air sampling were conducted at two COVID-19 isolation units and in a quarantine hotel. Viral RNA was detected by RT-PCR and infectivity was assessed by VERO E6 CPE test.

Results: In laboratory-controlled conditions, SARS-CoV-2 gradually lost its infectivity completely by day 4 at ambient temperature, and the decay rate of viral viability on surfaces directly correlated with increase in temperature. Viral RNA was detected in 29/55 surface samples (52.7%) and 16/42 surface samples (38%) from the surroundings of symptomatic COVID-19 patients in isolation units of two hospitals and in a quarantine hotel for asymptomatic and very mild COVID-19 patients. None of the surface and air samples from the three sites (0/97) were found to contain infectious titres of SARS-Cov-2 on tissue culture assay.

Conclusions: Despite prolonged viability of SARS-CoV-2 under laboratory-controlled conditions, uncultivable viral contamination of inanimate surfaces might suggest low feasibility for indirect fomite transmission.

Keywords: COVID-19; Contamination; Coronavirus; SARS-CoV-2; Surface; Viability.

Fig. 1

Stability of SARS-CoV-2 on non-porous surfaces under controlled laboratory conditions. Plastic and metal coupons (1 cm²) inoculated with 1 × 10⁶ PFU SARS-CoV-2 (by applying 10 μl of 1 × 10⁸ PFU/ml) were incubated at room temperature (A) or at 40-70 °C (B). At selected time points the coupons were extracted as described and residual viable virus titers on each sampled surface was determine by CPE assay on VERO E6 cells. Results are presented as mean ± std of viral titer log reduction index from 3 independent experiments.