Effectiveness of 222-nm ultraviolet light on disinfecting SARS-CoV-2 surface contamination

Am J Infect Control. 2021 Mar;49(3):299-301. doi: 10.1016/j.ajic.2020.08.022. Epub 2020 Sep 4.


Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease 2019 (COVID-19), has emerged as a serious threat to human health worldwide. Efficient disinfection of surfaces contaminated with SARS-CoV-2 may help prevent its spread. This study aimed to investigate the in vitro efficacy of 222-nm far-ultraviolet light (UVC) on the disinfection of SARS-CoV-2 surface contamination.

Methods: We investigated the titer of SARS-CoV-2 after UV irradiation (0.1 mW/cm2) at 222 nm for 10-300 seconds using the 50% tissue culture infectious dose (TCID50). In addition, we used quantitative reverse transcription polymerase chain reaction to quantify SARS-CoV-2 RNA under the same conditions.

Results: One and 3 mJ/cm2 of 222-nm UVC irradiation (0.1 mW/cm2 for 10 and 30 seconds) resulted in 88.5 and 99.7% reduction of viable SARS-CoV-2 based on the TCID50 assay, respectively. In contrast, the copy number of SARS-CoV-2 RNA did not change after UVC irradiation even after a 5-minute irradiation.

Conclusions: This study shows the efficacy of 222-nm UVC irradiation against SARS-CoV-2 contamination in an in vitro experiment. Further evaluation of the safety and efficacy of 222-nm UVC irradiation in reducing the contamination of real-world surfaces and the potential transmission of SARS-CoV-2 is needed.

Keywords: COVID-19; Disinfection; Environmental contamination; Far-UVC.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • COVID-19 / prevention & control
  • COVID-19 / virology
  • Decontamination / methods*
  • Disinfection / methods*
  • Humans
  • RNA, Viral / radiation effects*
  • SARS-CoV-2 / radiation effects*
  • Ultraviolet Rays*


  • RNA, Viral