Pathogen reduction of SARS-CoV-2 virus in plasma and whole blood using riboflavin and UV light

PLoS One. 2020 May 29;15(5):e0233947. doi: 10.1371/journal.pone.0233947. eCollection 2020.


Background: Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has recently been identified as the causative agent for Coronavirus Disease 2019 (COVID-19). The ability of this agent to be transmitted by blood transfusion has not been documented, although viral RNA has been detected in serum. Exposure to treatment with riboflavin and ultraviolet light (R + UV) reduces blood-borne pathogens while maintaining blood product quality. Here, we report on the efficacy of R + UV in reducing SARS-CoV-2 infectivity when tested in human plasma and whole blood products.

Study design and methods: SARS-CoV-2 (isolate USA-WA1/2020) was used to inoculate plasma and whole blood units that then underwent treatment with riboflavin and UV light (Mirasol Pathogen Reduction Technology System, Terumo BCT, Lakewood, CO). The infectious titers of SARS-CoV-2 in the samples before and after R + UV treatment were determined by plaque assay on Vero E6 cells. Each plasma pool (n = 9) underwent R + UV treatment performed in triplicate using individual units of plasma and then repeated using individual whole blood donations (n = 3).

Results: Riboflavin and UV light reduced the infectious titer of SARS-CoV-2 below the limit of detection for plasma products at 60-100% of the recommended energy dose. At the UV light dose recommended by the manufacturer, the mean log reductions in the viral titers were ≥ 4.79 ± 0.15 Logs in plasma and 3.30 ± 0.26 in whole blood units.

Conclusion: Riboflavin and UV light effectively reduced the titer of SARS-CoV-2 to the limit of detection in human plasma and by 3.30 ± 0.26 on average in whole blood. Two clades of SARS-CoV-2 have been described and questions remain about whether exposure to one strain confers strong immunity to the other. Pathogen-reduced blood products may be a safer option for critically ill patients with COVID-19, particularly those in high-risk categories.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Betacoronavirus / drug effects*
  • Betacoronavirus / growth & development
  • Betacoronavirus / radiation effects*
  • Blood Chemical Analysis
  • Blood Transfusion
  • COVID-19
  • COVID-19 Serotherapy
  • Coronavirus Infections / therapy
  • Coronavirus Infections / transmission
  • Coronavirus Infections / virology
  • Humans
  • Immunization, Passive
  • Pandemics
  • Plasma / chemistry
  • Pneumonia, Viral / transmission
  • Pneumonia, Viral / virology
  • RNA, Viral / analysis
  • Riboflavin / pharmacology*
  • SARS-CoV-2
  • Ultraviolet Rays*
  • Viral Load


  • RNA, Viral
  • Riboflavin

Grants and funding

This work was supported by the Congressionally Designated Medical Research Program under grant number PR180446 - Indications Against Highly Pathogenic Agents for a Transportable Pathogen Reduction and Blood Safety System for Whole Blood to RG. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.