Not a nurse, but from the animation it looks like one needle tip is used to draw the vaccine then swapped with a new one. I assume the air in the new needle tip is purged before injection and the air from the bottle now at the top of the syringe is enough to push all the vaccine in all the way thru the needle tip.
It heavily relies on the nurses skill not to draw too much air though so it seems bad.
uhhhhh, isn't air in the syringe a bad thing?
Not a nurse, but from the animation it looks like one needle tip is used to draw the vaccine then swapped with a new one. I assume the air in the new needle tip is purged before injection and the air from the bottle now at the top of the syringe is enough to push all the vaccine in all the way thru the needle tip.
It heavily relies on the nurses skill not to draw too much air though so it seems bad.