If mare was vaccinated, then she will have passed on some level of immunity, and foal can have its initial vaccinations started at 5 - 6 months of age.
If mare has not been vaccinated, both mare and foal should be given a tetanus antitoxoid within 24hrs of birth, and can begin tetanus vaccinations proper from 6 weeks of age, and flu' from 3 months.
S
Can I butt in and ask.... If you just tetanus, is it yearly or two yearly? (Someone asked me and I wasn't sure, so thought I would ask and it saves doing another post lol)