Orally available antivirals like Favipiravir and Molnupiravir have shown their antiviral activity against SARS-CoV-2. Their efficacy has been reported in COVID-19 patients, recently.

A study reported the combined antiviral effect of the aforementioned drugs in a SARS-CoV-2 Syrian hamster infection model, where the infected hamsters were treated twice daily either with the vehicle (the control group) or a suboptimal dose of each antiviral or a combination of antivirals. The following results were obtained-After treating animals at the time of infection, with an antiviral combination at suboptimal doses, a marked combined potency at the endpoint was observed. This drug combination reduced the infectious virus titers in the lungs of animals by ∼5 log10. Also, the infectious virus vanished from the lungs of >60% of treated animals. On delaying the treatment by one day, a reduction of titers in the lungs of 2.4 log10 was noted. Infected animals, on treatment, almost prevented the transmission to co-housed untreated sentinels. These antiviral drugs increased the mutation frequency of the left-over viral RNA retrieved from the lungs of treated animals.The combination treatment increased the frequency of C-to-T mutations in the viral RNA than the single treatment groups, which highlights the prominent antiviral potency of the combination. Thus this study created a foundation for designing more clinical studies testing the efficacy of the Molnupiravir/Favipiravir combination for treating COVID-19.

Source- EBioMedicine,2021;72. https://doi.org/10.1016/j.ebiom.2021.103595.