With same needle for different persons the chances of getting
HIV is 30/10,000. That is 0.003%.but it is unethical .because same syringe if contaminated with blood or bacteria can transmit dangerous diseases if not sterilized.don't accept same syringe for next time.
Next Steps
if still have doubts you can take certain medicine to prevent
hiv .and check for hiv test after 4- 5 months.consult a general physician for best results.