A virus is essentially an information system(encoded in DNA or RNA) surrounded by a protective coat and shaped by evolution to ensure its own replication and survival.
Antiviral drugs tend to be unique for the particular virus,or closely related family of viruses.This has made them much less available than antibacterial drugs.
Humans have a deep history of viral infections,but other than the molecular analysis of current or recently circulating pathogens,the data is fragmentary.
That may change as researchers probe more ancient DNA from Egyptian mummies,where there is evidence of lethal tuberculosis and malaria(neither of which is viral)dating 1,500 to 4,000 years back.The evidence so far suggests mummies suffered from smallpox and polio.
Using vaccination and other disease control measures,we have eliminated two virus infections that have,through the ages,caused massive economic damage and loss of life:human smallpox(1980) and bovine rinderpest(2011).
Another scourge,polio,is close to eradication.But problems remain with vaccine coverage(and the safety of the medical teams) in regions that are essentially war zones.
