Vaccines for travelers include:
- those that are used routinely, particularly but not only in children;
- others that may be advised before travel to disease-endemic countries;
- those that, in some situations, are mandatory.
Most of the vaccines that are routinely administered in childhood require periodic booster doses throughout life to maintain an effective level of immunity. Adults in their country of residence often neglect to keep up the schedule of booster vaccinations, particularly if the risk of infection is low. Some older adults may never have been vaccinated at all. It is important to realize that diseases such as diphtheria and poliomyelitis, which no longer occur in most industrialized countries, may be present in those visited by travellers. Pre-travel precautions should include booster doses of routine vaccines if the regular schedule has not been followed, or a full course of primary immunization for people who have never been vaccinated. Other vaccines will be advised on the basis of a travel risk assessment for the individual traveler. In deciding which vaccines would be appropriate, the following factors are to be considered for each vaccine:
- risk of exposure to the disease
- age, health status, vaccination history
- reactions to previous vaccine doses, allergies
- risk of infecting others
- cost.
Mandatory vaccination, as authorized by the International Health Regulations, nowadays concerns only yellow fever. Yellow fever vaccination is carried out for two different reasons:
- to protect the individual in areas where there is a risk of yellow fever infection; and
- to protect vulnerable countries from importation of the yellow fever virus.
Travellers should therefore be vaccinated if they visit a country where there is a risk of exposure to yellow fever. They must be vaccinated if they visit a country that requires yellow fever vaccination as a condition of entry; this condition applies to all travellers who arrive from (including airport transit) a yellow fever endemic country.
Vaccination against meningococcal disease is required by Saudi Arabia for pilgrims visiting Mecca annually (Hajj) or at any time (Umrah) and/or Medina. Some polio-free countries may also require travellers from polio-endemic countries to be immunized against polio in order to obtain an entry visa, e.g. Saudi Arabia (proof of oral poliovirus vaccination is required 6 weeks prior to application for an entry visa for visitors arriving from countries reporting poliomyelitis cases).
Travellers should be provided with a written record of all vaccines administered (patient-retained record), preferably using the international vaccination certificate (which is required in the case of yellow fever vaccination).