Ivermectin is absolutely an antiviral drug. It blocks cells' α/β nuclear import protein--also used by a great number of RNA-based viruses--while letting other nuclear import proteins function normally.

"The well-tolerated drug ivermectin may hold great potential for treatment of YFV [yellow fever virus] infections. Furthermore, structure-based optimization may result in analogues exerting potent activity against flaviviruses other than YFV." (2012)

https://pubmed.ncbi.nlm.nih.gov/22535622/