Because the antibodies produced in the body vary from person to person after vaccination, there is no guarantee that everyone will have a three-year expiration date. After the initial vaccination, most patients are generally able to maintain effective antibody levels against rabies virus infection for one year. Rabies antibodies can be tested and if the antibody titer is <0.5 U/mL, a booster shot is required. Some patients are immunized for a longer period of time and can remain immune for three years, but others may only be immune for a short period of six months, which is related to each individual's resistance. If you are bitten by a dog again after a year of rabies vaccination, you can get another booster shot for insurance purposes. After a booster shot, the antibody titer can rise rapidly and effectively defend against rabies vaccine infection.