You should be vaccinated if:
–traveling to endemic country (map) (see list).
–traveling to a country that require the Yellow Fever Vaccination Certificate to ALL travelers (see list).
–traveling to a country that require the Yellow Fever Vaccination Certificate for coming from a endemic yellow fever country, even if you´ve been in transit (see list).
The Official Yellow Fever Vaccination Centers will provide you the International Yellow Fever Vaccination Certificate. You should carry it with your passport.
If there is any contraindication for yellow fever vaccination you should get a medical certificate, preferably in three languages (English, French and Spanish), indicating that vaccination is CONTRAINDICATED (see model).