Immunizations and Travel If you are travelling outside Canada or the United States, you might want to consult with a travel health clinic to discuss your immunization needs. Schedule your appointment at least six to eight weeks before your trip, as vaccines can take several weeks to become effective. If you are travelling to Mexico or overseas, you should be aware of any pre- cautions advised by Health Canada (visit http://www.phac-aspc.gc.ca/tmp-pmv/ index.html) and speak to your physician as far in advance as possible as it may be necessary to attend a travel clinic and get immunizations over a period of time. 20