For those who need rapid immunity against hepatitis b
--travelers about to embark, for example--immunity can be given with a quicker series of injections & a later booster at one year. Some schedules are not fda
approved but include vaccination at day zero then days 7 & 21 from first dose.
Other schedules include days 0, 10, & 21. Very good immunity at day 21. Also done with mixed hep b/hep a.