Greetings Since a year has passed without symptoms after the puppy bite, your son is not at risk for rabies. The incubation period for rabies is typically a few weeks to a few months, and once symptoms appear, the disease is nearly always fatal. A rabies vaccine is not necessary at this time as it is only effective as a post-exposure prophylaxis (PEP) given shortly after the bite. There is no reliable test for rabies in humans before symptoms appear.