If you've died a few times in Sekiro, then you'll have encountered the wonderful world of dragonrot. In the final game, dragonrot is cured through a limited amount of dragon's blood droplets, which cures the world and all afflicted of dragonrot.
But originally, you had to cure NPCs one at a time.
The revelation comes courtesy of Souls and Bloodborne data digger Lance McDonald. Like every FromSoftware game, Sekiro has a ton of cut content and secrets hidden in the game code, and one of those is Dragonrot Pellets.
The pellets were supposedly something the Wolf could go to Emma to create. According to voice files that McDonald was able to restore, the original plan was for the Wolf to hand out these pellets one at a time to afflicted NPCs, curing them of the dragonrot.
Sekiro still contains a lot of the code related to giving and receiving dragonrot pellets, including confirmation prompts and some dialogue between various characters. The Sculptor, for instance, mentions that breathing is a little easier after you give him the medicine. There's even an extra dialogue option with the physician Doujin, letting you decide whether or not Wolf explains the purpose of the pellet.
McDonald surmises that the decision to simplify dragonrot was made fairly late into the game's development, given full translations and voiceovers are still contained in the final version of the code. It's especially intriguing to see after the recent discussion about Sekiro's difficulty. Having to heal NPCs one at a time would have made the game vastly more difficult - or at least punished the player implicitly for dying more often.