Travelers can be immunized against a certain number of diseases. The duration of the protection conferred by immunization varies. It is possible to determine the person's immune status beforehand, but if there is any doubt it is usually more convenient to give complete primary vaccination or a booster, as appropriate.

A distinction should be made between vaccinations required by countries by law for entry to their territory, vaccination recommended by World Health Organization for general protection against certain diseases, and other vaccinations which may be advisable in certain circumstances. A vaccination plan should be established, taking into account the traveler's destination, overall state of health and current immune status, the duration and type of travel, and the time available.

Smallpox
No country any longer requires a certificate of vaccination against smallpox.

Cholera
No country or territory any longer requires a certificate of vaccination against cholera.

Yellow fever
A certificate of vaccination against yellow fever is the only certificate that should be required for international travel. The requirements of some countries are in excess of the International Health Regulations. However, vaccination against yellow fever is strongly recommended to all travelers who intend to go to places other than the major cities in the countries where the disease occurs in man or is assumed to be present in primates.

Malaria
Epidemiological details are given for all countries with malarious areas (geographical and seasonal distribution, altitude, predominant species, status of resistance). The recommended chemoprophylactic regimen is also indicated. The following abbreviations are used: - = no chemoprophylaxis necessary; CHL = chloroquine; C+P = chloroquine plus proguanil; MEF = mefloquine; DOX = doxycycline.