According to a research paper published in science journal, 4′-fluorouridine (4′-FlU, EIDD-2749), a ribonucleoside analog that inhibits RSV, related RNA viruses, and SARS-CoV-2 with high selectivity index in cells and human airway epithelia organoids.

Once-daily oral treatment was highly efficacious at 5 mg/kg in RSV-infected mice or 20 mg/kg in ferrets infected with different SARS-CoV-2 variants-of-concern, initiated 24 or 12 hours after infection, respectively. These properties define 4′-FlU as a broad-spectrum candidate for the treatment of RSV, SARS-CoV-2, and related RNA virus infections.

Blood analysis of treated mice uncovered no antiproliferative effect of 4′-FlU on the hematopoietic system. These results establish 4′-FlU as a broad-spectrum orally efficacious inhibitor of major RNA viruses, making it a promising therapeutic option for RSV disease and COVID-19, and a much-needed contributor to improving pandemic preparedness.

Source: Sourimant, J., Lieber, C. M., Aggarwal, M., Cox, R. M., Wolf, J. D., Yoon, J. J., ... & Plemper, R. K. (2021). 4′-Fluorouridine is an oral antiviral that blocks respiratory syncytial virus and SARS-CoV-2 replication. Science, eabj5508.