There are studies; ultimately, nothing with COVID is binary - it's levels of protection, and even with a beard there are a lot of "depends" based on the length of beard, fit of mask, and proper wearing.
I do find that one kind of KN95 fits great even with my beard (which is short - ~5mm). I trim next to the nose so I have a good fit there, and my side/bottom are short enough that for the most part mask seems to "dig through" the hair and contact skin, kinda like the Studded tires dig through snow to get to ice.
But again, I'm aware that my protection is lower than if I shaved. Personal risks assessments are personal, mine is that I work remotely, am on video calls 6+ hours a day, and shaved I look like a 12 years old :). Meanwhile I very rarely go out, and if I do go out for groceries biweekly or so, and not at all now during omicron, distance + mask + booster provide a reasonable protection.
I do find that one kind of KN95 fits great even with my beard (which is short - ~5mm). I trim next to the nose so I have a good fit there, and my side/bottom are short enough that for the most part mask seems to "dig through" the hair and contact skin, kinda like the Studded tires dig through snow to get to ice.
But again, I'm aware that my protection is lower than if I shaved. Personal risks assessments are personal, mine is that I work remotely, am on video calls 6+ hours a day, and shaved I look like a 12 years old :). Meanwhile I very rarely go out, and if I do go out for groceries biweekly or so, and not at all now during omicron, distance + mask + booster provide a reasonable protection.