Hii , Welcome To HCM & Thanks For Asking Your Query Here As the repeated dog bites are within one months , that should not affect the immunization of primary vaccination however For repeated dog bite, only two doses of anti rabies Vaccine are to be given on day 0 and 3, whatever is the interval from primary vaccination , so u can still give one more shot after 3 days of last bite however The Duration of immunity afforded to humans by a two injection vaccination course is about to be between two to three years Following administration of a booster dose (recommended at one year) If you want to maintain a good antibody levels it is recommended to take a booster shot one year after the last shot, after that every three to five years intervals finally i would strongly suggest you to see your doctor and tell him complete history so he will be able to guide you though the correct vaccination schedule for your son I hope it help Thanks again