It's cool concept, and an impressive realization for a first jam alone. One little thing that could improve gameplay and make the players rely less on luck is showing a little time in advance where the antidotes are gonna drop. Another idea I came up with while playing is that the other survivors could turn into zombies if you don't let them take any antidote: that way, players might want to leave them some antidotes to avoid having another zombi on the field.
Good job, keep it up!