oww i will pull out my info but basically they have well are advised to have a tetanus/flu booster a couple of months before the birth so that the foal is covered for the first few months before it can have its own boosters.
Yes, EHV at 5, 7, 9 months, then a tet booster for mare prior to foaling. If she is covered for flu then unless her flu requirements fit in with her prefoaling tet, no need to do her for flu.