The hepatitis A and B vaccine is given in a series of 3 shots. The booster shots are given 1 month and 6 months after the first shot. If you have a high risk of hepatitis infection, you may be given 3 shots within 30 days, and a fourth shot 12 months after the first.
I received three polio vaccinations. The second and the third were called boosters.
Diphtheria, tetanus, and acellular pertussis - From the Mayo Clinic:
Children 10 years of age and older, and adults, may need an additional immunization called a booster against diphtheria, tetanus, and pertussis. Adults and teenagers should receive Tdap instead of the tetanus-diphtheria (Td) injection if it has been 10 years or more since their last tetanus-diphtheria vaccine.
