A booster dose is required every two to three years depending upon risk of exposure.
A booster dose in those successfully immunized in the past.
Previously vaccinated animals should receive a single booster dose of vaccine each year.
Hib vaccine (Haemophilus influenzae type B)-Hib is given as a series of four injections at ages two months, four months, and six months, with a booster dose at 12-15 months.
The next dose should be given between six and 18 months of age with a final booster dose at age four to six years, for a total of four doses.
