As Bill Joy, the brilliant thinker and engineer reminded me, great medicines have saved lives, but it’s the simpler things, like clean water, that have saved the most lives.
I recall, at some point in my life, reading some history which delved into the Bubonic Plague in Europe.
Plague is bacterial, not viral, and is spread by the bite of the the Rat Flea, which is thusly (and unsurprisingly) named because it’s a flea which lives on rats.
During the period when Plague was spreading through Europe, it was also a time when people killed cats when found, because cats were considered to be demonic.
Fewer cats, more rats, more plague.