Prevention is better than cure. There are some nasty illnesses out there, and if you catch one while abroad it might just spoil your holiday. If you are extremely unlucky, it might kill you.
Ideally, we would like to see you 6-8 weeks before you go abroad. It’s best to have an idea of what countries you’re going to, but if you change your mind while away and need further vaccines, check online to see if there are local clinics that can provide the vaccines.
Certain countries insist on an International Certificate of Vaccination for yellow fever (vaccine given and certificate stamped at least 10 days before you enter the country) so be sure to check if you are going to one of these countries. You may be refused admission to the country without a valid, stamped, official yellow passport unless there are exceptional circumstances. This passport is only available from medical centres licensed to administer the Yellow Fever vaccine