How many doses of vaccine are needed?

Depends. Depneds on which vaccine you are asking about...
Depends on situation. Vaccine doses vary with the type of vaccine and the age of the child when the vaccine is first given.

Related Questions

How many doses of meningococcal vaccine are needed

1 or 2. Well, there is a small discrepancy right now. The cdc, the people who recommend how to get shots, recommends that kids 11-18 need two doses. One at 11yo and one aft 16yo. But, the fda has not approved either brand, Menveo or menactra, to be given that way. Both are only approved as a one dose vaccine. This will clear up soon and every kid will get 2 doses, and you can do that now off fda label. Read more...
How old are you? One usually given in childhood; then second end of high school / @ college entry. Lasts 10-15 years, so if working with high risk populations (kids/teens/young adults), could get booster in 35-ish age. Read more...