Assessment of Favipiravir and Remdesivir in Combination for SARS-CoV-2 Infection in Syrian Golden Hamsters.

Favipiravir (FVP) and remdesivir (RDV) have demonstrable antiviral activity against SARS-CoV-2. Here, the efficacy of FVP, RDV, and FVP with RDV (FVP + RDV) in combination was assessed in Syrian golden hamsters challenged with SARS-CoV- 2 (B.1.1.7) following intraperitoneal administration. At day 4 post infection, viral RNA and viral antigen expression were significantly lower in lungs for all three treatment groups compared to the sham treatment. Similarly, viral titres in the lungs were lower in all treatment groups compared to the sham treatment. The FVP + RDV combination was the only treatment group where viral RNA in nasal turbinate and lung, virus titres in lung, and viral antigen expression (lung) were all lower than those for the sham treatment group. Moreover, lower viral titre values were observed in the FVP + RDV group compared to other treatment groups, albeit only significantly lower in comparison to those in the RDV-only-treated group. Further assessment of the potential utility of FVP in combination with RDV may be warranted. Future studies should also consider whether the combination of these two drugs may reduce the speed at which drug resistance mutations are selected.