Researchers at Colorado State University (CSU) showed that exposure to riboflavin and ultraviolet light (R + UV) can reduce SARS-CoV-2 infectivity in human plasma and whole-blood products while maintaining blood product quality. The CSU team aimed to determine whether it would be possible to kill the virus in blood products. Although scientists do not yet know if SARS-CoV-2 can be transmitted by blood transfusion, viral RNA has been detected in serum. Researcher Izabela Ragan, postdoctoral fellow in the Department of Biomedical Sciences at Colorado State University. Courtesy of Ron Bend/CSU. The research team treated nine plasma and three whole-blood products using an existing pathogen reduction technology system from Terumo BCT. The blood product or plasma was placed in a specially designed storage bag. The riboflavin solution was added and the mixture was then exposed to UV light. The pathogen reduction technology device shook the bag to circulate the blood cells, causing cells to come to the surface where they were exposed to the UV light. 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. Riboflavin and UV light reduced the infectious titer of SARS-CoV-2 below the limit of detection for plasma products at 60% to 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 in plasma and 3.30 ± 0.26 in whole blood units. “We eliminated a huge amount of virus and we could not detect the virus post-treatment,” researcher Izabela Ragan said. Pathogen-reduced blood products could be a safer option for critically ill patients with COVID-19 and could help prevent transmission of the disease through blood and blood products. Professor Ray Goodrich, who invented the pathogen reduction technology, said that the system is currently only approved for use outside of the U.S., and is mainly used in Europe, the Middle East, and Africa. “Our research may help inform people outside the U.S who are using it,” Goodrich said. “They may breathe a sigh of relief knowing that while we continue to study this, there is some potential mitigation in place just in case.” The research was published in PLOS ONE (www.doi.org/10.1371/journal.pone.0233947).