The earliest Herbal Medicine compilation/textbook dates back to 1550 BCE in Egypt, so a generic 'Herbal Medicine' could be an Ancient Technology.
Several Resources already in the game, like Spices and Honey, have antibiotic/antiseptic properties, so could be applied to 'disease prevention/amelioration'
There are in addition, Great Scientists like Hippocrates, Galen, Dioscorides, Celsus, al-Zahrawi, Paracelsus, Pare, any or all of whom could provide 'Medical Bonuses' to your Civ, or the Great Works from some of them (Galen, al-Zahrawi, Dioscorides) could provide 'extra' medical knowledge to combat disease.
BUT all of that seems to me to be ballooning the original concept into something more complex and intricate than the game needs. As
@Evie posted, Civ IV had a good, basic Disease mechanic. Tweak some of the individual factors a bit based on the Terrain/Climate Model Civ VII uses, but I cannot see the point in adding an entire array of Great People, Great Works, specialized knowledge, specialized Resources, etc to get to the same thing Civ IV already had. Especially if Catastrophic Pandemic Population Loss is off the table, as it should be in any game that purports to be competitive in any way.