Thank you for your inquiry. From what we gather from the question, you were asking about the possibility of HIV transmission in the event that you had pierced the skin with a needle that had previously been used on another individual. In this scenario, you describe that the family member claims the needle to be unused, but the syringe to be previously used.
For the purpose of clarity, it is our interpretation that you had pricked yourself with the needle immediately after drawing liquid from a multi-dose glass vial in which the needle has been attached to a previously used needle chamber.
From the information given, this scenario is determined to be High Risk (there is evidence of transmission through these activities and are the majority of cases of transmission).
For needle injuries, the type of needle is important. As you have described, the needle used in this event is a hypodermic needle. The risk of HIV transmission is higher in this case than with a non-hollow needle (such as a sewing needle) (1). The risk of acquiring HIV from a hypodermic needle with blood containing the virus is between 0.2%-0.5% (1). The risk increases with the amount of blood introduced and the concentration of virus in the blood (2). The size of the needle, depth of penetration, and injection of blood are also important considerations (1).
In your post, you describe the needle to be new, but the syringe to have been used. Transmission is still considered to be possible, and the act still considered to be of High Risk. Although the needle has been replaced, the syringe has not. In this event, there is a likelihood that the syringe could act as a vacuum-sealed chamber, allowing HIV positive fluid (blood) to remain intact. Theoretically, blood containing HIV, in this case, may have entered your bloodstream through the needle-prick injury.
It appears as though you had received HIV screening immediately after this event occurred. For High Risk events like the one you have described, we typically would recommend you seek PEP within 72 hours post-exposure, as well as HIV screening.
From what you have described, you have taken the necessary steps we would recommend in this case. If your doctor has not recommended PEP, and you are still within the 72-hour post-exposure period, we would recommend you do ask to inquire about your PEP your options.
Recommendation: Refer to a health care provider for more questions regarding PEP.
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1.) Risk of HIV Transmission associated with Needle-Stick Injuries.
2.) Case Control Study of HIV Transmission After Needle-Stick Injury.