After twenty years of being bitten by a dog, there is actually no need to worry about rabies attacks anymore. Although the incubation period of rabies can be more than one year, this is after all a minority of cases, and by twenty years of time such cases are almost unseen, so you can stop worrying about rabies attacks at this point. Still worried about the corresponding attack situation, in fact, you can also go for rabies vaccination, but at this time the process of rabies vaccination, not too recommended complete injection of five shots or the use of the four injection method to inject four shots, which are post-exposure prophylaxis measures. The purpose of this injection can be chosen as pre-exposure prophylaxis, that is, only three injections of rabies vaccine, respectively, on the zero, seven, twenty-one (or twenty-eight) days of injection, after the injection of three shots of the corresponding antibodies can also be produced, worried about being infected again after such preventive measures can be done, injection of three shots after a year to enhance the injection of a shot, the corresponding rabies neutralizing antibodies can be maintained for a longer period of time.