It's a good idea to see your doctor as soon as possible before you leave for your trip. The ideal time frame would be four to six weeks before you depart, because some vaccinations take time to become effective, and some are given over a period of days or even weeks.
If your departure is less than four weeks away, it's still a good idea to see your doctor. She may be able to provide some inoculations that could be of benefit to you--as well as other advice or recommendations--to help keep you healthy as you travel.
The CDC has divided travelers' noculations into three types: routine, recommended and required vaccinations. Routine shots required for adults as well as children are the standard vaccinations Americans usually receive, such as measles, mumps and rubella vaccines; also included in this category are the hepatitis A, B and influenza vaccinations. Recommended vaccinations are necessary to protect you from diseases that are rare in the U.S., but occur frequently in other parts of the world. The type of vaccine you receive will depend on the country or countries you will be visiting. The only vaccinations currently required under International Health Regulations are for yellow fever and meningitis, which are required for individuals traveling to sub-Saharan Africa, parts of South America or Saudi Arabia.
People with immune-compromised conditions should be particularly careful before receiving inoculations for travel. Some diseases that decrease the function of the immune system may open the door to serious health effects if certain inoculations are given. If your health status precludes you from receiving the recommended injections, the CDC advises making changes to your itinerary or potentially canceling your trip, if necessary. Women of reproductive age should stay current with their inoculations in the event a trip and an unplanned pregnancy occur simultaneously; vaccinations given preconception are generally deemed safer to the fetus. Pregnant women should be aware of when the influenza season occurs in the area where they travel, as well as what the risk of tuberculosis is, and obtain shots accordingly.
