Pathfinder 2E Attacks that do Afflictions such as Spider Bites

[Yardiff]

If your hit by an attack such as a spider bite and block all damage with either a shield or with resistance does that also block any poison damage from happening?

Is affliction the right word for this?

 

[kenada]

The affliction rules say that you make the save when you are exposed to the affliction. The poison monster ability says effectively the same thing, leaving what is meant by exposed undefined. The section on alchemical poison is more specific: you have to take piercing or slashing damage to be exposed to an injury poison (i.e., have to make a saving throw). I’d use that as my basis to rule that monster poisons work analogously to alchemical ones (based on what makes sense for the creature).

Getting back to the original question, if an effect reduced the damage taken to 0, then I’d rule you weren’t exposed to the spider’s venom from the bite.

 

[dungeonHamster]

Getting back to the original question, if an effect reduced the damage taken to 0, then I’d rule you weren’t exposed to the spider’s venom from the bite.

That's how I interpreted it as well.

 

[CapnZapp]

The rules for Injury poison are clear (page 550):

If that Strike is a success and
deals piercing or slashing damage, the target must attempt
a saving throw against the poison.

So if resistance reduces damage to zero (or you smear your poison on a Club! ), you don't have to save against an injury poison.

Note the Subtle Delivery feat:

Subtle Delivery - Feats - Archives of Nethys: Pathfinder 2nd Edition Database

You can capably deliver toxins with a <a style="text-decoration:underline" href="Weapons.aspx?ID=66">blowgun</a>. Your blowgun Strikes can apply <a style="text-decoration:underline" href="Traits.aspx?ID=97">injury</a> poisons even if they deal no damage due to a creature's resistance. If you...

2e.aonprd.com

Do note few or no monsters list which method of exposure their attacks-with-poison deliver. A GM is free to rule that a monster's attack isn't delivering an injury poison but perhaps a contact or inhalation poison, where the amount of damage taken isn't relevant.