Vial of Antidote

Colour Requirements

When injecting zombies, green vials can be used on zombies with 10HP or lower, while vials at yellow or worse need the target at 5HP. Any vial that fails its injection does 0-4 dmg to the zombie. Also, red vials only have a 50% chance of working on a successful inject attempt. Attempting to inject a zombie above the necessary HP required for the vial being used will cause yellow, orange, and red vials to inflict 5 dmg on a successful hit, and 0-4 when failed. Green vials, on a successful hit do 10dmg, and 0-10 when failed.

Injections in humans will always work, regardless of the antidote color or your injector proficiency skill level. There is no fail chance on a human.

Note that injecting with a red vial may not convert even if the injection is "successful". The injection success only indicates if you didn't miss the zombie; for everything except red antidotes, a successful injection will always convert. Red vials have a 50% chance of not converting upon a hit, thus allowing the following example:

With a red antidote:
You injected Uroguy but failed to cure his infection (25 minutes 28 seconds ago).
You killed Uroguy (25 minutes 28 seconds ago).

Here, you see that red vials can fail even if you "successfully" injected the zombie. It's a very bittersweet "success". Hence why important inject targets should not be injected with red vials except as a last resort.