But if you watch the video more closely, the plunger does not move and there is no spring to retract the needle. Also, depending on the type of retractable used, it would not be possible to withdraw the mRNA poison from the vial without the needle retracting or not being able to pierce the vial. It's not impossible they used a retracting needle syringe, but the video doesn't show what one might look like in real use.