As a physician, my opinion would be:
If you received a tetanus injection from a properly functioning healthcare facility, the risk of acquiring
HIV, hepatitis B (HBV), or hepatitis C (HCV) from the injection is extremely low. The concern would mainly arise if a previously used or contaminated needle/syringe had been used.
If you are genuinely unsure about the sterility and the injection was given recently, I would take a baseline test and then follow up rather than worry unnecessarily.
Suggested testing schedule
Today / as soon as possible — baseline
* HIV 1 & 2 4th-generation Ag/Ab test
* HBsAg ± anti-HBs/anti-HBc
* Anti-HCV
* This establishes your status before/around the suspected exposure.
HIV
* A laboratory-based 4th-generation HIV Ag/Ab test can usually detect infection 18–45 days after exposure.
* I would repeat the HIV 4th-generation test at approximately 6 weeks.
* If there is a significant documented exposure, an HIV NAT/RNA test can detect infection earlier and should be discussed with an infectious-disease/PEP clinician.
Hepatitis C
* If the exposure is considered significant, HCV RNA can be checked at 3–6 weeks, followed by anti-HCV testing at 4–6 months if indicated.
Hepatitis B
* Testing should be individualized according to your hepatitis-B vaccination and antibody status. HBsAg is an important marker for infection.
One important point
If this happened within the last 72 hours and there is a real possibility that a previously used needle/syringe was used, don’t wait for testing—seek an HIV PEP assessment urgently. PEP is time-sensitive.
If you tell me when you received the tetanus injection (e.g., today, 2 days ago, 1 week ago) and whether it was at a hospital/clinic/pharmacy, I can give you an exact day-by-day testing plan.