I've heard a bit about needle aspiration for Covid injections...

I've heard a bit about needle aspiration for Covid injections recently, and whether this not being done has played a role in myocarditis reactions.

This video has good information on it.

Hitting veins and arteries in the deltoid isn't likely, but the needle can still end up in smaller blood vessels.





Worth checking out the whole video below;
note particularly from 7:20...

My suggestion would be to follow his advice in the last minute of the video.