Pen needle installation and removal safety cover and pen needle assembly utilizing the same

A needle tip assembly for a pre-loaded syringe or pen needle injection device, the needle tip assembly comprising:

• a body comprising a double-ended needle and being installable and removable from the pre-loaded syringe or pen needle injection device, wherein the body comprises outwardly deflectable teeth engageable with threads on the pre-loaded syringe or pen needle injection device;
• a needle cap configured to cover a skin puncturing end of the double-ended needle and being removable to expose the skin-puncturing end;
• and
• an outer cover structured and arranged to at least:
• install onto the body of the needle-tip assembly device;
• be re-installable and non-releasably locked to the body while the body remains installed on the pre-loaded syringe or pen needle injection device, wherein, when the outer cover is re-installed to the body, the outwardly deflectable teeth outwardly deflect to disengage the outwardly deflectable teeth from the threads;
• and
• remove the body from the pre-loaded syringe or pen needle injection device after the outer cover is re-installed to the body;
• wherein, after re-installation of the outer cover and removal of the body from the pre-loaded syringe or pen needle injection device, the double-ended needle is positioned inside the outer cover without use of the needle cap, thereby preventing puncturing by a user of the double-ended needle.