My understanding is that the _concept_ of a virus wasn't even established until the late 19th century, because we first needed the germ theory, and then we needed to understand bacteria well enough to have a filter whose pores were known to be smaller than bacteria could pass through, but which some _other_ infection agent could still pass through.

https://en.wikipedia.org/wiki/History_of_virology#Discovery

Hippocrates could recommend elderberry for a bunch of ailments, but he didn't have the concept of a "universal antiviral".