In experiments in animals favipiravir has shown activity against West Nile virus, yellow fever virus, foot-and-mouth disease virus as well as other flaviviruses, arenaviruses, bunyaviruses and alphaviruses. Activity against enteroviruses and Rift Valley fever virus has also been demonstrated. Favipiravir has showed limited efficacy against Zika virus in animal studies, but was less effective than other antivirals such as MK-608. The agent has also shown some efficacy against rabies, and has been used experimentally in some humans infected with the virus.