Ultra-low waste needle and syringe system that automatically and passively renders a needle safe during the injection process

A needle and syringe system that provides ultra-low dosage waste and automatic needlestick protection. A syringe assembly is provided that contains a barrel and a plunger. A tubular spacer is disposed in the barrel. A needle head assembly is provided that includes a collar and a needle. A safety slide is positioned between the needle and the collar. The safety slide has a sheathing tube that surrounds part of the needle. The safety slide can move relative the needle. In a first position, the sheathing tube does not extend beyond the sharpened end of the needle. In a second position, the sheathing tube extends beyond the sharpened end of the needle. When advanced, the plunger head moves the tubular spacer. The tubular spacer passes over the base of the needle and presses against the safety slide. The safety slide is moved from the first position to the second position.