General considerations
Vaccination is the administration of a vaccine to stimulate a protective immune response that will prevent disease in the vaccinated person if contact with the corresponding infectious agent occurs subsequently. Thus vaccination, if successful, results in immunization: the vaccinated person has been rendered immune to disease caused by the infectious pathogen. In practice, the terms “vaccination” and “immunization” are often used interchangeably.
Disease prevention
Vaccination is a highly effective method of preventing certain infectious diseases. For the individual, and for society in terms of public health, prevention is better and more cost-effective than cure. Vaccines are generally very safe and serious adverse reactions are uncommon. Routine immunization programmes protect most of the world’s children from a number of infectious diseases that previously claimed millions of lives each year. For travellers, vaccination offers the possibility
of avoiding a number of dangerous diseases that may be encountered abroad. Immunized travelers will also be less likely to contaminate other travelers or local population with a number of potentially serious diseases. However, vaccines have not yet been developed against several of the most life-threatening infections, including malaria and HIV/AIDS.
Vaccination and other precautions
Despite their success in preventing disease, vaccines do not always fully protect 100% of the recipients. The vaccinated traveller should not assume that there is no risk of contracting the disease(s) against which he/she has been vaccinated. All additional precautions against infection should be followed carefully, regardless of any vaccines or other medication that have been administered. These same precautions are important in reducing the risk of acquiring diseases
for which no vaccines exist and that represent health problems commonly faced by international travellers. It is also important to remember that immunization is not a substitute for avoiding potentially contaminated food and water.