I would say that only if you eat the berries. I find that I get a rash if I stratch myself on the foliage but that is an allergy that I have.

I hope I can reassure you. As children my brother & I regularly played in among yew trees and he tried to make a long bow out of the stems. He often got cuts and scratches from the yew and he has certainly gone on happily for at least 55 years.

The berries are indeed poisonous if you eat them.
so you will be fine as long as you keep the scratches clean.

Actually it is the seeds which are poisonous. The flesh of the berries is not. Not that I would try them, just in case.

That is very true Owd but I suspect quite a few people would not know the difference between the seeds and the 'berry'.

There are toxins in the foliage. That's why yew clippings were used to make chemotherapy drugs and why cattle have died after yew cuttings were dumped on grazing land. But the amount, if any, of toxin transferred by a scratch is not going to cause any harm.

As for the berries (pedantry warning - they can be called arils because the seed is exposed at the base), I met someone who ate hundreds every year always spitting out the seeds. I don't see the attraction. The flesh is very sweet but the texture is slimy.

Interesting. I wondered why the birds that eat the berries never came to harm.

Birds lack the enzyme which converts the cyanide in the seeds in to deadly poison. We do have it.