Something I've never understood, based on personal experience and watching these videos, but to my knowledge when receiving a vaccination you definitely do not hold your own sleeve out of the way, that could spread germs around the site, generally a big no-no.
Also, ive had injections in the same area, and a small tourniquet is still used to remove blood flow from the lower arm.
I don't know, something stinks. 💁🏼‍♀️