An invention which provides for making low cost apparatus and one-hand activation methods for shielding a syringe needle as a safety precaution after each needle use. A shield, which may be used as a protective cover for the needle during initial transport to site of use, is linearly actuated to three distinct stops by action of a single hand, thereby leaving the second hand of a user free for patient care. The shield is releasible from two of the three stops to make possible uncovering of the needle preparatory to use and temporary needle protection between needle uses. The shield has an elongated hollow barrel shape which is sized to fit snugly about, yet slide smoothly over a body of a syringe associated with the needle. The barrel shape of the shield is longitudinally interrupted by a scissure in which an arm which is hingeably affixed to the shield resides. The arm is selectively bent to provide operative surfaces which permit the shield to be released from two of the three stops and further displaced to selected stops by inward depression of the arm. The invention utilizes a collet with a slot and a pawl which interacts with at least one set of ratchet teeth on the arm to provide one of the releasible stops. Generally release from stops is actuated by inward pressure on a predetermined portion of the arm.