Since their proliferative ability is not high, clones that are less susceptible to favipiravir grow well alone or are not viable, but an additional alteration that modulates RdRp activity restores the replication capability and the susceptibility to favipiravir (Abdelnabi, et al., 2017; Delang, et al., 2014; Goldhill, et al., J o u r n a l P r e -p r o o f Journal Pre-proof 2019).