NO mask (or any other item of PPE) gives perfect protection.
Masks DO decrease the possibility of transmission, but not to zero. But wearing one is certainly much better than not.
Certainly? Is that “scientific consensus”? We’ve seen that before.
The anti-mask faction makes perfect the enemy of good. It’s like rabid environmentalists for whom 0 is the only acceptable level of what the evil chemical of the day is.
But let’s not let that spoil the narrative.