Rabies vaccines given two years ago are less effective and need to be given immediately if you are accidentally bitten. Generally speaking, the rabies vaccine is effective for about 6 months. That is, within 6 months after the completion of the vaccination, the titer and number of rabies virus antibodies in the body can be maintained at a high level. In other words, if you are bitten by an animal such as a dog, you can be effectively protected from rabies virus infection. However, if it takes more than 6 months, the titer and quantity of rabies vaccine in the body will gradually decline, and after 2 years, it will not be able to achieve the purpose of preventing rabies virus infection. Therefore, if you are bitten after 2 years, it is safer to consult a doctor, clean the wound and get rabies vaccination immediately. Consult a medical professional for advice.