Molnupiravir (EIDD-2801), an orally bioavailable nucleoside analog, was originally developed as an antiviral against influenza viruses but showd antiviral potential against various other RNA viruses, including SARS-CoV2 and other coronaviruses. 

A study described the effect of EIDD-2801 in a Syrian hamster SARS-CoV-2 infection model. 

• They found that on administering EIDD-2801 for four consecutive days, initiating from the day of infection, infectious virus titers and viral RNA loads in the lungs were markedly reduced and lung histopathology was markedly improved in a dose-dependent manner on assessing at 4 dpi. 
• On postponing the treatment with 500 mg/kg/dose until 24h post-infection, a modest but significant antiviral effect was achieved. 
• On combining suboptimal doses of favipiravir (300 mg/kg, BID) and EIDD-2801 (150 mg/kg, BID), a complete reduction (∼5 log10) of infectious virus titers were achieved in the lungs of the majority of the subjects, while either compound alone caused a reduction of 1.2 and 1.3 log10 respectively. 

Thus the potential of EIDD-2801 for the treatment and/or prevention of SARS-CoV-2 alone or in combination with favipiravir need immediate attention.

Source- bioRxiv 2020.12.10.419242; doi: https://doi.org/10.1101/2020.12.10.419242