To prevent rabies after being scratched by a dog, five doses of rabies vaccine are administered. The first dose of rabies vaccine is recommended to be given within 24 hours so that rabies can be prevented to the maximum extent. The first dose of the rabies vaccine will produce rabies neutralizing antibodies in the blood within 1-2 weeks after the injection, thus providing protection. Therefore, it is recommended that the first injection be given as early as possible, preferably within 24 hours. However, if given a few hours or days later, it can also be effective, but the rate of protection may be reduced. Because the incubation period of rabies is greater than one month, mostly between 1-3 months, rabies can be prevented after the rabies vaccine has allowed the body to produce neutralizing antibodies. However, the incubation period for rabies is approximate, and some rabies incubation periods are even shortened to one week, especially for severe bites to the head and face. Therefore, the general principle of rabies vaccination is that the earlier the better.