Automatic-locking safety needle covers and methods of use and manufacture

A single-use needle cover, comprising:

• a housing configured to couple to a syringe and at least partly contain the needle, wherein the housing includes a guide member, a first locking member, and a second locking member;
• a sleeve configured to move between an extended position and a retracted position with respect to the housing, wherein the extended position covers a distal tip of the needle and the retracted position exposes the distal tip of the needle, and wherein the sleeve is biased toward the extended position;
• wherein movement of the sleeve from the extended position to the retracted position rotates the sleeve with respect to the housing, transfers the guide member from a first track to a second track included in the sleeve, and engages a first locking member;
• wherein movement of the sleeve from the retracted position to the extended position engages a second locking member;
• and
• wherein the first and second locking members inhibit movement of the cover to prevent reuse.