Multiple virological and epidemiological studies support the consensus that viruses adapt to novel hosts through successful cross-species transmission events followed by key secondary genomic mutations that enhance replication and fitness.
The claim posits that viruses adapt to new hosts through repeated cross-species host jumps and secondary mutations. All retrieved papers that directly investigate this mechanism (such as papers 0, 1, 5, 6, and 9 on influenza and other viruses) show that cross-species transmission coupled with specific adaptive genomic mutations drives viral host range expansion and adaptation. There is no evidence in the provided sources refuting this mechanism. Therefore, the verdict is SUPPORTED.