Feasibility of ultraviolet light-emitting diode irradiation robot for terminal decontamination of COVID-19 patient rooms

Objective: To investigate the feasibility of using an ultraviolet light-emitting diode (UV LED) robot for the terminal decontamination of coronavirus disease 2019 (COVID-19) patient rooms. Methods: We assessed the presence of viral RNA in samples from environmental surfaces before and after UV LED irradiation in COVID-19 patient rooms after patient discharge. Results: This study analyzed 216 environmental samples from 17 rooms (two from airborne infection isolation rooms [AIIRs] in the intensive care unit [ICU] and 15 from isolation rooms in the community treatment center [CTC]). Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA was detected in 40 (18.5%) of 216 samples after patient discharge: 12 (33.3%) of 36 samples from AIIRs in the ICU, and 28 (15.6%) of 180 samples from isolation rooms in the CTC. In one AIIR, all samples were PCR-negative after UV LED irradiation. In the CTC rooms, 14 (8.6%) of the 163 samples were PCR-positive after UV LED irradiation. However, viable virus was not recovered from the culture of any of the PCR-positive samples. Conclusions: Although no viable virus was recovered, SARS-CoV-2 RNA was detected on various environmental surfaces. The use of a UV LED disinfection robot was effective in a spacious areas such as an ICU, but its effects varied in small spaces like CTC rooms. This suggests that the UV LED robot may need enough space to disinfect rooms without re-contamination by machine wheels or insufficient disinfection by shadowing.