A retractable safety syringe may have a needle, needle holder, syringe body, a shaft seal, and a plunger assembly. A proximal portion of the body and a piston of the plunger may define a vacuum chamber. The plunger assembly may comprise a shaft coupled to a piston. The shaft may have at least one non-engaging portion and at least one engaging portion. The plunger assembly is movable between a storage position and working positions. In the storage position, little or no force is exerted on the shaft seal by the non-engaging portion. In the working positions, the engaging portion is in sealing engagement with the shaft seal to seal the vacuum chamber. Stopper movement of the retractable safety syringe may be reduced or eliminated if the retractable safety syringe is prefilled.